Galling resistant steel plates demonstrating excellent impact toughness of weld and excellent resistance to delayed fracture

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, namely to galling resistant steel plates used in construction, machines manufacturing, shipbuilding, for pipes manufacturing. Steel contains wt %: from 0.20 to 0.30 C, from 0.05 to 1.0 Si, from 0.40 to 1.2 Mn, 0.010 or below P, 0.005 or below S, from 0.40 to 1.5 Cr, from 0.005 to 0.025 Nb, from 0.005 to 0.03 Ti, 0.1 or below Al, 0.01 and below N, Fe and inevitable admixtures - rest. Steel can additionally contain one or several components selected from the group containing Mo, W, Cu, Ni, V, rare earth elements, Ca and Mg, and has quenching coefficient determined as follows: DI*=33.85×(0.1×C)0.5×(0.7×Si+1)×(3.33×Mn+1)×(0.35×Cu+1)×(0.36×Ni+1)×(2.16×Cr+1)×(3×Mo+1)× (1.75×V+1)× (1.5×W+1), equal to 45 to 180. Steel has microstructure, its main phase is created by martensite, and particles of Nb and Ti carbonitrides having average size 1 micron or below, in quantity 1000 pc./mm2 or over, and average size of particles of preceeding austenite below 200 microns.

EFFECT: required impact toughness and resistance to delayed fracture are ensured.

14 cl, 2 dwg, 6 tbl

 

The technical field to which the invention relates

The present invention relates to abrasion resistant steel plate or steel sheet having a sheet thickness of 4 mm or more, which preferably is used in building materials, industrial machinery, shipbuilding, steel pipes, civil engineering, architecture or the like, and more particularly, to abrasion resistant steel plate or steel sheet, which shows excellent impact strength and excellent resistance to delayed fracture.

The level of technology

When hot rolled plate steel is used for production of structural steel, vehicles, machinery or the like in the Assembly machines, industrial machine tools, shipbuilding, steel pipes, civil engineering, architecture or the like, a situation may arise when you need steel plate which have the characteristics of resistance to abrasion. Traditionally, to make a steel product features excellent resistance to abrasion, usually increases the hardness, and the hardness of the steel products can be greatly enhanced by obtaining steel products in a martensite single-phase microstructure. The increase in the content of dissolve solid�and carbon is also effective directly increases the hardness of the martensitic microstructure.

Accordingly, abrasion resistant steel plate shows a high tendency to crack, so that the steel plate usually shows poor impact strength of the weld; therefore, when the abrasion resistant steel plate used for production of welded steel construction, usually, abrasion resistant steel plate is stratified to the surface of steel parts, which is in contact with rock, soil and sand or the like as a covering. For example, in relation to the container buffered truck, there are cases when the container is mounted with the use of mild steel and abrasion resistant steel plate is stratified only to the outer surface of the container, which is in contact with the soil and sand.

However, in production technology, in which an abrasion resistant steel plate to delaminate after Assembly, welded steel construction, increase production effort and cost of production. Accordingly, there is a demand for abrasion resistant steel plate, which can be used as a support member welded steel construction, and the abrasion resistant steel plate has been pre�Lorena, for example, in patent documents 1-5.

Patent document 1 relates to an abrasion resistant steel plate that exhibits excellent resistance to delayed fracture, and to a method for the production of abrasion-resistant steel plate. In patent document 1 indicated that to improve the resistance to delayed fracture of steel, which additionally contains one, two or more types of components selected from the group consisting of Cu, V, Ti, and CA in the composition, where Si contains little, little R, little S, Cr, Mo and Nb, the steel is subjected to carburizing quenching with heating (it is also called SCN), and, if necessary, is carried out vacation.

[0005] Patent document 2 relates to a steel having the characteristic of high resistance to abrasion, and to a method of producing steel products. In patent document 2 described steel which has a composition of the composition: from 0.24 to 0.3 s, Ni, Cr, Mo, V, and the system corresponds to a parametric formula that includes the content of the above elements, and includes martensite containing from 5 to 15% by volume of austenitic or martensitic structure and bainite structure, thus improving the characteristic of abrasion resistance. In patent document 2 also describes that the steel containing the above components, is cooled with a speed� 1°C/sec or more at a temperature between the temperature of austenization and 450°C.

Patent document 3 relates to an abrasion resistant steel product that demonstrates excellent impact strength and excellent resistance to delayed fracture, and to a method for producing an abrasion resistant steel products. In patent document 3 describes a steel product that has a composition containing Cr, Ti, and as a mandatory component, where the surface layer is formed of tempered martensite, the inner part is formed of tempered martensite and tempered lower bainite structure, and is determined by the ratio of the geometric dimensions of the diameter of the grains of prior austenite in the direction of the wall thickness in the rolling direction. In addition, in patent document 3 describes that the steel containing specified components, is subjected to hot rolling at a temperature of 900°C or below and a total elongation factor equal to 50% or more, after that, subjected to carburizing quenching with heating and tempering.

Patent document 4 relates to an abrasion resistant steel product that demonstrates excellent impact strength and excellent resistance to delayed fracture, and to a method for producing an abrasion resistant steel products. In patent document 4 described a steel product that has a composition containing Cr, i and V as essential components, where the surface layer is formed of martensite, and the inner part is formed of a mixed structure of martensite and lower bainite structure or lower bainite single phase structure, and is determined by the elongation factor of the grains of prior austenite, expressed by the ratio of the geometric dimensions between the diameter of the grains of prior austenite in the Central position of the sheet thickness and the diameter of the grains of prior austenite in the rolling direction. In addition, in patent document 4 describes that the steel of the specified composition is subjected to hot rolling at a temperature of 900°C or below and a total elongation factor 50% or more and, thereafter, subjected to carburizing quenching with heating.

Patent document 5 relates to abrasion-resistant steel that exhibits excellent weldability, excellent characteristics of resistance to abrasion and excellent resistance to corrosion, and to a method of producing steel resistant to abrasion. In patent document 5 describes a steel, which contains from 4 to 9 wt.% Cr as a mandatory element contains one element or two elements of Cu and Ni and corresponds to a parametric formula that includes the content of specific components. In addition, in patent document 5 describes that the steel of specified composition exposes�I hot rolling at a temperature of 950°C or below and a total elongation factor equal to 30% or more and after that, the steel is re-heated at a temperature of AC3 or more, and subjected to quenching.

The prior art documents Patent documents

Patent document 1 is JP-A-5-51691

Patent document 2 JP-A-8-295990

Patent document 3 JP-A-2002-115024

Patent document 4 JP-A-2002-80930

Patent document 5 JP-A-2004-162120

Summary of the invention

The problem addressed by the invention

The most serious problem related to the reduction in toughness when welding steel material, is the deterioration of toughness in the contact area on the border of penetration. In abrasion-resistant steel having a martensitic structure in the hardened condition, the deterioration of impact strength, which is called the embrittlement at low temperature holidays there as a problem also in the zone of influence of the heat of welding (subsequently also called vecs), which is re-heated to a temperature of about 300°C, away from the border of penetration. I believe that the embrittlement at low temperature vacation is called a synergistic interaction between the morphological changes of carbides in the martensite phase and intergranular allocation of impurity elements or the like.

In the field, which is re-heated to a temperature embrittlement under low temperature vacation, with the joint influence�and hydrogen, which penetrates into the weld from the shielding gas during welding, residual stresses generated by the heat of welding, it may be delayed fracture (fractures that occur in the weld, generally referred to as low-temperature cracking), and especially the likely occurrence of delayed fracture in abrasion-resistant steels with high strength.

Therefore, when using abrasion resistant steel plate as a support member welded structures it is necessary to increase the impact strength, contact area, and in the zone affected by the heat of welding, which is re-heated to a temperature of about 300°C, away from the border of penetration. However, traditional abrasion resistant steel plate has a high susceptibility to cold cracking of the weld, and therefore to prevent cold cracking is necessary to release the hydrogen from sheet steel and to reduce residual stress steel sheet by carrying out processing, such as pre-and post-heating before and after welding.

In patent documents 1 and 2 are not described increase in toughness of the weld in abrasion-resistant steels, and in patent documents 3 and 4 also describes the microstructure, which is required to increase the toughness of the base mA�of Arial. Although in patent document 5 investigated the weldability and abrasion resistance of the weld, in this study it was aimed to increase the impact toughness of the weld. Thus, abrasion resistant steel, as proposed in patent documents 1 to 5 and the like are not optimal for the improvement of the impact toughness and resistance to delayed fracture of the weld.

Accordingly, the purpose of the present invention is the development of abrasion resistant steel plate that exhibits excellent notch toughness of the weld and excellent resistance to delayed fracture, causing loss of productivity and increase manufacturing costs. In the present invention the impact strength of the weld toughness means in the zone of influence of the heat of welding, and excellent notch toughness of the weld specifically means that the impact strength is excellent in the contact area and in the area of embrittlement under low temperature tempering.

Solutions to problems

For the purpose of achieving the above objective, the authors present invention have performed a detailed study of various factors that determine the chemical components of the steel plate, a method of producing plate steel and Mick�structure heavy steel in order to guarantee the toughness of the weld and resistance to delayed fracture in relation to the abrasion resistant steel plate, and got the following data.

1. To ensure excellent performance of abrasion resistance, is compulsory basic education or basic microstructure the microstructure of the steel plate in the martensite. To this end an important strict control of the chemical composition of the steel plate, and thus the characteristic of hardening.

2. To achieve excellent impact toughness of the weld, it is necessary to suppress the agglomeration of particles of crystallites in the contact area, and for this purpose it is effective to use the pinning effect by the dispersion of fine sediment particles in thick sheet steel.

3. For superior toughness and suppression of delayed fracture in the temperature region of embrittlement under low temperature leave the zone under the influence of the heat of welding is important that appropriate control of the amount of alloying elements such as C, Mn, Cr, R.

The present invention was accomplished by further study of the above data. Thus, the present invention relates to the following:

1. Abrasion resistant plate became�, with excellent impact toughness of the weld seam and excellent resistance to delayed fracture, and having a composition containing, in wt.%: from 0.20 to 0.30% C, 0.05 to 1.0% Si, 0.40 to 1.2% of Mn, from 0.010% or less P, 0.005% or less S, from 0.40 to 1.5% of Cr, 0.005 to 0.025% Nb, 0.005 to 0.03% Ti, 0.1% or less Al, 0.01% or less N, and the rest Fe and inevitable impurities, where the hardening coefficient DI*, expressed by the formula (1) is 45 or more and basic phase microstructure is formed from martensite

DI*=33,85×(0,1×C)0,5×(0,7×Si+1)×(3,33×Mn+1)×(0,35×Cu+1)×(0,36×Ni+1)×(2,16×Cr+1)×(3×Mo+1)×(1,75×V+1)×(1,5×W+1)...(1 ),

where the numbers of the corresponding elements signify the contents (mass%) of those elements.

2. Abrasion resistant steel plate having excellent toughness of the weld seam and excellent resistance to delayed fracture described in claim 1, wherein the steel composition further comprises one, two or more components selected from the group consisting of (in wt.%): from 0.05 to 1.0% Mo, from 0.05 to 1.0% W, and from 0,0003 to 0,0030% V.

3. Abrasion resistant steel plate having excellent toughness of the weld seam and excellent resistance to delayed fracture described in claim 1 or 2, where the composition of the steel further includes, in wt.%: one, two, or more components selected from the group consisting of 1.5% or less Cu, and 2.0% or less Ni, and 0.1% or less of V.

4. Abrasion resistant steel plate having excellent toughness of the weld seam and excellent resistance to delayed fracture, described in any one of claims.1-3, where the composition of the steel further includes, in wt.%: one, two, or more components selected from the group consisting of 0.008% or less of rare earth elements (REE), from 0.005% or less CA, and 0.005% or less Mg.

5. Abrasion resistant steel plate having excellent adenovirally weld seam and excellent resistance to delayed fracture, described in any one of claims.1-4, where the surface hardness of the steel plate is 400 HBW 10/3000 or more on the hardness scale Brinell.

6. Abrasion resistant steel plate having excellent toughness of the weld seam and excellent resistance to delayed fracture, described in any one of claims.1-5, where the hardening coefficient DI* is 180 or less.

7. Abrasion resistant steel plate having excellent toughness of the weld seam and excellent resistance to delayed fracture, described in any one of claims.1-6, where the content of components in steel plate corresponds to the following formula (2).

C+Mn/4Cr/3+10P0,47(2),

where the numbers of the corresponding elements signify the contents (mass%) of those elements.

Advantages of the invention

In accordance with the present invention can be obtained abrasion resistant steel plate having excellent impact strength and excellent resistance to delayed fracture of the weld. The present invention makes a great contribution to the improvement of production efficiency and secure�ti of the process of producing steel structure, thus, the invention acquires a significant industrial effect.

Brief description of the drawings

Fig.1 shows a view explaining the test cracking of fillet weld t-shaped profile.

Fig.2 shows the position where the test specimen impact strength Charpy taken from the weld.

The implementation of the invention the Present invention determines the composition and microstructure of steel.

Composition

In the following description, % means mass%. To: from 0.20 to 0.30%

Carbon is an important element for increasing the hardness of martensite and to ensure excellent performance of abrasion resistance steel plate. To obtain these effects it is necessary to plate the steel contains carbon, from 0.20% or more. On the other hand, when the content exceeds 0.30% of deteriorates weldability not only, but also the toughness of the contact area and impact strength in the field of low-temperature tempering of the weld. Accordingly, the carbon content is limited to a value that is within a range from 0.20 to 0.30%. Preferably, the content of C is limited to a value that is within a range from 0.20 to 0.28%.

Si: 0.05 to 1.0%

Silicon acts as a deoxidizer, and Si is necessary not only for steel, but also Si �shows the impact on the increase of hardness plate steel by solid solution hardening, when silicon is present in steel in the form of a solid solution. In addition, Si has an overwhelming influence on the deterioration of the toughness of the weld, in the area of embrittlement during tempering in the impact zone of the heat of welding. To obtain these effects it is necessary to plate the steel contains 0.05% or more Si. On the other hand, when the Si content exceeds 1.0%, significantly deteriorates the toughness of a multipass weld in the zone affected by the heat of welding. Accordingly, the Si content is limited to a value which is in the range from 0.05 to 1.0%. Preferably, the Si content is limited to a value which is in the range from 0.07 to 0.5%.

Mn: 0.40 to 1.2%

Manganese has an impact on improving the hardenability of steel, and to ensure the hardness of the basic material necessary to plate the steel contains 0.40% or more Mn. On the other hand, when the content of Mn exceeds 1.2%, deteriorating not only the toughness, ductility and weldability of the base material, but also accelerated intergranular excretion of phosphorus, resulting in faster generation of delayed fracture. Accordingly, the content of Mn is limited to a value which is in the range from 0.40 to 1.2%. Preferably, the content of MP is limited to the value�, which is in the range from 0.40 to 1.1%.

R: from 0.010% or less

When the content of P exceeds 0,010%, phosphorus's a segregation at the grain boundary, the released phosphorus becomes the region of initiation of delayed fracture, which degrades the toughness of a multipass weld. Accordingly, the upper limit of the content of P is set to 0,010%, and it is desirable that the content of P was set at the lowest possible level. Since an excessive decrease in the content of phosphorus increases cleaning costs and becomes uneconomical, the content of P is preferably maintained at a level of 0.002% or more.

S: 0.005% or less

Sulfur S degrades low-temperature impact strength and ductility of the base material, and therefore it is desirable to set a low content of S, the allowable upper limit of 0.005%.

Cr: 0.40 to 1.5%

Chromium is an important alloying element of the present invention, and has an impact on improving the hardenability of steel, and also has an overwhelming influence on the deterioration of the toughness of the weld in the area of embrittlement during tempering in the impact zone of the heat of welding. This is because the inclusion of Cr retards the diffusion of carbon in steel plate, and therefore, when re-heated steel plate to a temperature in the region whe� embrittlement occurs under low temperature vacation can be suppressed the morphological changes of carbides in the martensite. To obtain this effect it is necessary to plate the steel contains Cr 0.40% or more. On the other hand, when the Cr content exceeds 1.5%, the effect becomes saturated, so that it becomes not only economically disadvantageous, but also decreases weldability. Accordingly, the chromium content is limited to a value which is in the range from 0.40 to 1.5%. Preferably, the Cr content is limited to a value which is in the range from 0.40 to 1.2%.

Nb: from 0.005 to 0.025%

Niobium is an important element affecting how to improve the impact toughness of the weld in the zone of influence of the heat of welding, and suppress the occurrence of delayed fracture by creating a dispersed microstructure of the base material and in the zone of influence of the heat of welding, causing the deposition of carbon nitride, as well as by fixing a solid solution of nitrogen. To obtain these effects it is necessary to plate the steel contains from 0.005% or more Nb. On the other hand, when the niobium content exceeds 0.025% of that larger particles are deposited carbon nitride, and you may experience a situation when large particles of carbon nitride become a region of fracture initiation. Accordingly, the Nb content is limited�intensified by value, which is in the range from 0.005 to 0.025%. Preferably, the Nb content is limited to a value which is in the range from 0.007 to 0,023%.

Ti: 0.005 to 0.03%

Titanium has an overwhelming influence on the coarsening of grains in the contact area of the weld by forming titanium nitride due to the fixation of the solid solution of nitrogen, and also has an overwhelming influence on the deterioration of the toughness and the occurrence of delayed fracture in the temperature of low-temperature tempering, by reducing the amount of solid solution of nitrogen. To obtain these effects it is necessary to plate the steel contains titanium from 0.005% or more. On the other hand, when the Ti content exceeds 0.03%, and the precipitated titanium carbide TiC, so that deteriorates the toughness of the base material. Accordingly, the Ti content is limited to a value which is in the range from 0.005 to 0.03%. Preferably, the content of Ti is limited to a value which is in the range of from 0.007 to 0.025%.

Al: 0.1% or less

The aluminum acts as a deoxidizer and is most commonly used in the deoxidizing treatment of the molten steel when receiving plate steel. In addition, by the formation of aluminum nitride AlN, due to the fixation of the solid solution of nitrogen in steel, Al has suppress�its influence on the coarsening of grains in the contact area of the seam, and also has an overwhelming influence on the deterioration of the toughness and the occurrence of delayed fracture in the temperature of low-temperature tempering, by reducing the solid solution N. on the other hand, when the Al content exceeds 0.1%, the aluminum is mixed in the weld metal during welding, and thus, deteriorates the toughness of the weld metal. Accordingly, the Al content is limited to 0.1% or less. Preferably, the Al content is limited to a value that is within a range from 0.01 to 0.07%.

N: 0.01% or less

Nitrogen forms a nitride with niobium or titanium and has an effect on the suppression of the process of particle agglomeration in the zone affected by the heat of welding. However, when the N content exceeds 0.01%, and significantly deteriorates the toughness of the base material and the toughness of the weld, and therefore, the N content is limited to 0.01% or less. Preferably, the N content is limited to a value that is within a range from is 0.0010 to 0,0070%. The remainder being iron and unavoidable impurities.

According to the present invention, to further improve the properties of steel plate, in addition to the above major components of the system, the steel plate may contain one, two or more types of components selected from the group, with�standing from Mo W, In, Cu, Ni, V, REE, CA and Mg.

Mo: 0.05 to 1.0%

Molybdenum is an effective element to improve the hardenability and, thus, increase the hardness of the base material. To obtain the specified effect preferably, the Mo content may be 0.05% or more. However, when the content of Mo exceeds 1.0%, molybdenum adversely affects the toughness, ductility and crack resistance of the weld base material. Therefore, the Mo content is set to 1.0% or less.

W: 0.05 to 1.0%

Tungsten is an effective element to improve the hardenability, thus, increases the hardness of the base material. Preferably, to obtain such an effect, the content W can be 0.05% or more. However, when the content of W exceeds 1.0%, the tungsten has a negative effect on the impact strength, ductility and crack resistance of the weld base material. Accordingly, sets the contents of W to 1.0% or less.

In: 0,0003 to 0,0030%

Boron is an effective element to improve the hardenability, thus, adding trace amounts of boron increases the hardness of the base material. Preferably, to obtain the specified effect of the boron content can reach to 0.0003% or more. However, when the content Prevyshaet 0,0030%, Bor has a negative effect on the impact strength, ductility and crack resistance of the weld base material. Accordingly, the content of boron is set to 0,0030% or less.

All metals Cu, Ni and V are elements that contribute to the strength of steel, and steel plate may contain an appropriate amount of Cu, Ni, V, depending on the desired strength steel plate.

Cu: 1.5% or less

Copper is an effective element for improving the hardenability and, thus, to increase the hardness of the base material. Preferably, to obtain the specified effect of the copper content may be 0.1% or more. However, when the Cu content exceeds 1.5%, the effect is saturated, and copper causes brittleness, resulting in deteriorating the surface properties of steel plate. Accordingly, set the copper content up to 1.5% or less.

Ni: 2.0% or less

Nickel is an effective element for improving the hardenability and, thus, to increase the hardness of the base material. Preferably, to obtain the specified effect, the Ni content may be 0.1% or more. However, when the Ni content exceeds 2.0%, the effect becomes saturated, so that the additive becomes economically disadvantageous. Accordingly, set with�holding the Nickel and 2.0% or less.

V: 0.1% or less

Vanadium is an effective element for improving the hardenability and, thus, to increase the hardness of the base material. Preferably, to obtain the specified effect, the V content may be 0.01% or more. However, when the V content exceeds 0.1%, deteriorates the toughness and ductility of the base material. Accordingly, set the vanadium content of 0.1% or less.

All elements REE, CA and Mg contribute to the improvement of the toughness, and these elements are selectively added in accordance with desired characteristics of the steel plate. When you add REE preferably, the REE content may be as low as 0.002% or more. On the other hand, when the content of REE exceed 0,008%, this effect is saturated. Accordingly, sets the upper limit REE to 0.008%.

When adding calcium preferably, the content of CA may be from 0.0005% or more. On the other hand, when the content of CA exceeds that of 0.005%, the effect is saturated. Accordingly, sets the upper limit of calcium to 0.005%.

When adding magnesium preferably, the Mg content may be 0.001% or more. On the other hand, when the Mg content exceeds 0.005% or less, this effect is saturated. Accordingly, sets the upper limit Mg do,005%.

DI*=33,85×(0,1×C)0,5×(0,7×Si+1)×(3,33×Mn+1)×(0,35×Cu+1)×(0,36×Ni+1)×(2,16×Cr+1)×(3×Mo+1)×(1,75×V+1)×(1,5×W+1)...(1),

where the numbers of the corresponding elements signify the contents (mass%) of those elements.

The specified parameter: DI* (coefficient hardenability) is defined to form the basic structure of the basic material in the martensite, resulting in the basic structure given feature excellent abrasion resistance in the range of the above composition, and the value of this parameter is determined� is $ 45 or more. When the value of this parameter is set below 45, the hardening depth from the surface layer in the thickness direction of the sheet becomes less than 10 mm and therefore, shortens the life of steel plate in the quality abrasion resistant steel plate.

When the parameter value exceeds 180, the basic structure of the basic material consists of martensite and therefore the basic structure demonstrates appropriate characteristics of resistance to abrasion. However, deteriorates the characteristics of low-temperature cracking during welding and low temperature toughness of the weld. Accordingly, the value of the parameter DI* preferably set equal to 180 or less. More preferably, the parameter DI* is set to the value that is in the range from 50 to 160.

C+Mn/4Cr/3+10P0,47(2),

where the numbers of the corresponding elements signify the contents (mass%) of those elements.

When the basic structure of the base material steel plate is formed of martensite and has a composition that demonstrates excellent impact strength in conta�Tnom plot and in the area of embrittlement under low temperature tempering at the implementation of the welding parameter value: C+Mn/4-Cr/3+10P is set equal to 0.47 or less in the range of the above composition. Although the basic structure of the basic material presented by the martensite and demonstrates appropriate characteristics of abrasion resistance, even when the parameter value exceeds 0,47, the impact strength of the weld is significantly reduced. Preferably, the value of the specified parameter can be of 0.45 or less. Microstructure

According to the present invention, to improve the characteristics of resistance to abrasion is determined that the reference phase or the microstructure of the steel plate represents the martensite. Such structure as bainite or ferrite, is different from martensite reduces the feature of abrasion resistance, and therefore is preferably such a structure is not mixed with martensite as possible. However, when the total area ratio of these structures is less than 10%, we can neglect the influence of these structures. In addition, when the surface hardness of the steel plate is less than 400 HBW10/3000 on the hardness scale Brinell, shortens the life of steel plate, abrasion resistant. Accordingly, it is desirable surface hardness�the cooling is set equal to 400 HBW10/3000 or more on a scale of hardness Brinell.

According to the present invention in the microstructure of the developed steel contact area is a mixed structure of martensite and bainitic. Such structure as ferrite, is different from that of martensite and bainitic reduces the feature abrasion resistance, and therefore is preferably such a structure is not mixed as much as possible. However, when the total area ratio of these structures is less than 20%, we can neglect the impact of these patterns.

In addition, in steel, designed according to the present invention, to ensure the toughness of the contact area is preferred that the particles of carbonitride of Nb and Ti having an average particle size of 1 μm or less are present in quantities of 1,000 pieces/mm2or more, the average particle size of prior austenite is less than 200 μm, and average particle size lower microstructure surrounded by a grain boundary with a large slope having a radial concavity 15° or more is less than 70 microns.

According to the present invention abrasion resistant steel can be obtained in the following production conditions. In the explanation that follows, the symbol "°C" relating to temperature means the temperature at the half of the thickness of the sheet. Preferably, the molten was�, having the above composition, was obtained by a known method for the production of molten steel and the molten steel is formed inside commodity steel products, such as the flat blank having a predetermined size, using the continuous casting process or method of producing ingots in the blooming mill.

Then, the resulting raw steel product is immediately subjected to hot rolling without cooling or subjected to hot rolling followed by heating at a temperature of from 950 to 1250°C after cooling, the thus formed plate steel having a desired sheet thickness. Immediately after hot rolling is carried out water cooling, or quenching is carried out after reheating. After that, if necessary, is on vacation at a temperature of 300°C or below.

Implementation option 1

Steel flat sheet metal of various compositions shown in table 1, which are obtained with the use of Converter steel, refining in a ladle and continuous casting method, is heated at a temperature of 1000 to 1250°C, and then steel flat billet is subjected to hot rolling under the conditions of production, shown in table 2. After rolling, cooling water quenching (SCN)) served on some sheets of steel. As for the other sheets�Ali, after rolling, they are cooled by air, and after re-heating is the water cooling (quenching (RQ)).

For the obtained steel sheets are held measure the surface hardness, the assessment of the characteristics of abrasion resistance, measure the impact toughness of the base material, test cracking of fillet weld t-shaped profile (evaluation of characteristics of resistance to delayed fracture), the test of an artificial zone of influence of the heat of welding and testing the impact toughness of the weld for real welds in accordance with the following methods. The results obtained are shown in table 3.

Surface hardness 1

Measurement of surface hardness is carried out for each sheet of steel in accordance with the conditions of JIS Z 2243 (1998) to measure the surface hardness below the surface layer (surface hardness measured after removing slag from the surface layer). In this dimension are solid tungsten balls having a diameter of 10 mm, at a predetermined load of 3000 kilograms-force.

The toughness of the base material 1

For each steel sheet are taken on the sample with a V-shaped incision in the direction perpendicular to the rolling direction at the position remote from the surface of the steel plate at 1/4 of the thickness �East in accordance with the stipulation of JIS Z 2202(1998), and conduct test impact strength Charpy at three relevant temperatures for each steel sheet in accordance with the stipulation of JIS Z 2242 (1998), determine the magnitude of the absorbed energy at a test temperature of 0°C and estimate the toughness of the base material. The test temperature 0°C are selected according to the use of steel plate in a warm area.

Steel plate, for which the mean of the three values of the absorbed energy (also referred to as vE0) at test temperature 0°C is 30 j or more is defined as steel plate having superior toughness of the base material (in the framework of the present invention).

Feature abrasion resistance 1

With regard to the characteristics of abrasion resistance, for each of the sheet steel shall be tested for abrasion rubber wheel in accordance with ASTM G65. The test is carried out using samples that have dimensions: sheet thickness 10 mm × width (w) 75 mm × length 20 mm (L) (t (sheet thickness) × 75 mm (w) × 20 mm (L) when the sheet thickness is smaller than 10 mm), and with the abrasive sand, obtained from 100% of SiO2as the abrasive material.

The mass of the sample measured before and after the test, and determine the wear of the sample. The test results let us estimate�another place for the championship the basis of the rate of wear: (wear of mild steel sheet)/(wear each sheet steel) with a wear sheet mild steel (SS400) as standard (1,0). This means that the higher the wear resistance, the more excellent is the characteristic of abrasion resistance, and in relation to the scope of the present invention, plate steel, for which endurance is 4.0 or more is considered excellent.

Delayed fracture 1

To test the cracking of fillet weld t-shaped profile, restrictive for welding samples, each of which is mounted in a T-shape, as shown in figure 1, using metal arc welding with a covered electrode, and then conduct the test on welding at room temperature (25°C × 60% humidity level) or after heating to 100°C.

The welding method is a metal arc welding covered electrode (welding material: LB52UL (4.0 mm, f), where heat input is 17 kJ/cm, and welding are done 3 layers and 6 passes. After the test, the samples are incubated at room temperature for 48 hours, and then from the plate to the select test 5 cross-weld specimens for sample surveys (shoulder length 200 mm divide into 5 equal parts), and examined for the presence or absence of cracks occur in the area under the influence of heat welding using projection equipment and Opti�climate microscope. In samples prepared without preheating, as well as in samples prepared with preliminary heating at a temperature of 100°C, in 5 of the respective samples cross-sampling, no samples were found with cracks in the area under the influence of the heat of welding; these samples were characterized as excellent in resistance to delayed fracture.

Notch toughness of the weld 1-1

In the artificial test zone of influence of the heat of welding is modeled by a low-temperature vacation contact area, which is single-pass arc welding in a protective gas atmosphere CO2with supplied heat 17 kJ/cm In the simulation of the contact area, the specified area is kept at a temperature of 1400°C for 1 seconds and cooled at a cooling rate of 30°C/s from 800 to 200°C. on the other hand, when modeling the area of embrittlement under low temperature leave the specified area of embrittlement maintained at a temperature of 300°C for 1 seconds and cooled at a speed of 5°C/s from 300 to 100°C.

The test sample is rolled square section, selected in the rolling direction, is subjected to the above heat cycle by a mechanism of high-frequency induction heating, and thereafter, conduct a test of toughness for �Arpi for sample V-neck incision in accordance with the stipulation of JIS Z 2242 (1998). Test toughness by Charly carried out for three specimens of each steel plate at the prescribed test temperature of 0°C.

Steel plate, for which the mean of the three values of the absorbed energy (vE0) in the contact area and in the area of embrittlement under low temperature vacation is 30 j or more is defined as steel plate having superior toughness of the weld (in the scope of the present invention).

Notch toughness of the weld 1-2

In addition, to confirm the real toughness of the welded joint is carried out welding of the flange on the steel sheet using metal arc welding covered electrode (heat input: 17 kJ/cm, pre-heating: 150°C, welding material: LB52UL (4,0 MMF)). Sample for test impact strength Charpy taken at the position 1 mm below the surface of the steel sheet, and test the impact toughness of the Charpy V-neck incision is carried out in accordance with the stipulation of JIS Z 2242 (1998) using the provisions of the incision as the contact area. Figure 2 shows the position of selection of the sample for testing the impact strength Charpy and position of the incision.

Test impact strength Charpy real welded joint with a V-shaped incision is carried out using three specimens and regulated�eat temperature test at 0°C. Steel plate, for which the mean of the three values of the absorbed energy (vE0) is 30 j or more is defined as steel plate having superior toughness in the contact area (in the scope of the present invention).

Table 2 shows the conditions of production of steel plate used in the test, and table 3 shows the results of the respective tests. In the examples of the present invention (steel Nos. 1 to 5) samples have a surface hardness of 400 HBW10/3000 or more display characteristics excellent abrasion resistance, and toughness of the base material at 0°C, equal to 30 j or more. In addition, to test the cracking of fillet weld t-shaped profile does not have any cracks, and the samples of the present invention have excellent impact strength in relation to artificial the zone affected by the heat of welding, and real toughness of a welded joint, and therefore it is proved that the samples of the present invention exhibit superior impact strength of the weld.

On the other hand, in relation to the samples of comparative examples (steel Nos. 6-14), the composition of which is outside the scope of the present invention, it is proved that the samples of the comparative examples do not meet teletelemarketing in respect of one or more properties and tests of surface hardness, abrasion resistance, testing for cracking of fillet weld t-shaped profile, the impact toughness of the base material, the test impact strength Charpy reproduced with a thermal cycle test impact strength Charpy real welded joint.

Implementation option 2

Steel flat sheet metal of various compositions shown in table 4, are obtained with the use of Converter steel, refining in a ladle and continuous casting method, is heated at a temperature of 1000 to 1250°C, and then steel flat billet is subjected to hot rolling under the conditions of production, shown in table 5. Cooling water (quenching (SCN)) served on some sheets of steel immediately after rolling. As for the other plate after rolling, they are cooled by air, and after re-heating is the water cooling (quenching (RQ)).

For the obtained steel sheets are held measure the surface hardness, the assessment of the characteristics of abrasion resistance, measure the impact toughness of the base material, test cracking of fillet weld t-shaped profile (evaluation of characteristics of resistance to delayed fracture), the test of an artificial zone of influence of the heat of welding and testing the impact toughness of the weld to actually�of welded joints in accordance with the following methods. The results obtained are shown in table 6.

Surface hardness 2

Measurement of surface hardness is carried out in accordance with the conditions of JIS Z 2243 (1998), thus, the surface hardness is measured below the surface layer (surface hardness measured after removing slag from the surface layer). In this dimension are solid tungsten balls having a diameter of 10 mm, at a predetermined load of 3000 kilograms-force.

The toughness of the base material 2

For each steel sheet are taken on the sample with a V-shaped incision in the direction perpendicular to the rolling direction at the position remote from the surface of the steel plate on 1/4 of the sheet thickness in accordance with condition JIS Z 2202(1998), and test impact strength Charpy at three relevant temperatures for each steel sheet in accordance with the stipulation of JIS Z 2242 (1998), and determine the amount of absorbed energy at a test temperature of 0°C and -40°C and estimate the toughness of the base material. The test temperature 0°C are selected according to the use of steel plate in a warm region, and the test at -40°C are selected according to the use of heavy-gauge steel in a cold region.

Steel plate, for which the mean of the three values of the absorbed energy (�also referred to as vE 0) at test temperature 0°C is 30 j or more, the average of the three values of the absorbed energy (also referred to as vE-40) when the test temperature -40°C is 27 j or more is defined as steel plate having superior toughness of the base material (in the framework of the present invention). Regarding steel plate having a thickness of less than 10 mm, select a sample with a V-shaped notch having a reduced size (5 mm × 10 mm), and subjected to test impact strength Charpy. Steel plate, for which the mean of the three values of the absorbed energy (vE0is 15 j or more and the average of the three values of the absorbed energy (vE-40) is 13 joules or more is defined as steel plate having superior toughness of the base material (in the framework of the present invention).

Feature abrasion resistance 2

With regard to the characteristics of abrasion resistance, for each of the sheet steel shall be tested for abrasion rubber wheel in accordance with ASTM G65. The test is carried out using samples that have dimensions: sheet thickness 10 mm × width (w) 75 mm × length 20 mm (L) (t (sheet thickness) × 75 mm (w) × 20 mm (L) when the sheet thickness less than 10 mm), and with IP�altanium abrasive sand, obtained from 100% of SiO2as the abrasive material.

The mass of the sample measured before and after the test, and determine the wear of the sample. The test results are evaluated based on the indicator of wear: (wear of mild steel sheet)/(wear each sheet steel) with a wear sheet mild steel (SS400) as standard (1,0). This means that the higher the wear resistance, the more excellent is the characteristic of abrasion resistance, and in relation to the scope of the present invention, plate steel, for which endurance is 4.0 or more is considered excellent.

Delayed fracture 2

To test the cracking of fillet weld t-shaped profile, restrictive for welding samples, each of which is mounted in a T-shape, as shown in figure 1, using metal arc welding with a covered electrode, and then conduct the test on welding at room temperature (25°C, at a humidity of 60%) or after heating to 100°C.

The welding method is a metal arc welding covered electrode (welding material: LB52UL (4.0 mm, f), where heat input is 17 kJ/cm, and welding are done 3 layers and 6 passes. After the test, the samples are incubated at room�Oh temperature for 48 hours, and then from plate to select test 5 cross-weld specimens for sample surveys (shoulder length 200 mm divide into 5 equal parts), and examined for the presence or absence of cracks occur in the area under the influence of heat welding using projection equipment and optical microscope. In samples prepared without preheating, as well as in samples prepared with preliminary heating at a temperature of 100°C, in 5 of the respective samples cross-sampling, no samples were found with cracks in the area under the influence of the heat of welding; these samples were characterized as excellent in resistance to delayed fracture.

Notch toughness of the weld 2-1

In the artificial test zone of influence of the heat of welding is modeled by a low-temperature vacation contact area, which is single-pass arc welding in shielding gas WITH2with supplied heat 17 kJ/cm In the simulation of the contact area, the specified area is kept at a temperature of 1400°C for 1 seconds and cooled at a cooling rate of 30°C/s from 800 to 200°C. in addition, when modeling the area of embrittlement under low temperature leave the specified area of embrittlement is heated at 300°C for 1 CE�Andy and cooled at a speed of 5°C/s from 300 to 100°C.

The test sample is rolled square section, taken in the rolling direction, is subjected to the above heat cycle by a mechanism of high-frequency induction heating, and thereafter, conduct test impact strength Charpy sample V-neck incision in accordance with the stipulation of JIS Z 2242 (1998). Test impact strength Charpy carried out for three specimens of each steel plate at the prescribed test temperature 0°C and -40°C respectively.

Steel plate, for which the mean of the three values of the absorbed energy (vE0) is 30 j or more and the average of the three values of the absorbed energy (vE-40) is 27 j or more is defined as steel plate having superior toughness of the weld (in the framework of the present invention).

Regarding steel plate having a thickness of less than 10 mm, select a sample with a V-shaped notch having a reduced size (5 mm × 10 mm), and subjected to test impact strength Charpy. Steel plate, for which the mean of the three values of the absorbed energy (vE0is 15 j or more and the average of the three values of the absorbed energy (vE-40) is 13 joules or more is defined as steel plate, having prevoshodnogo toughness of the weld (in the scope of the present invention).

Notch toughness of the weld 2-2

In addition, to confirm the real toughness of the welded joint is carried out welding of the flange on the steel sheet using metal arc welding covered electrode (heat input: 17 kJ/cm, pre-heating: 150°C, welding material: LB52UL (4,0 MMF)). Sample for test impact strength Charpy taken at the position 1 mm below the surface of the steel sheet, and test the impact toughness of the Charpy V-neck incision is carried out in accordance with the stipulation of JIS Z 2242 (1998) using the provisions of the incision as the contact area. Figure 2 shows the position of selection of the sample for testing the impact strength Charpy and position of the incision.

Test impact strength Charpy real welded joint with V-neck is carried out using three samples under controlled temperature test at 0°C and -40°C. the steel Plate, for which the mean of the three values of the absorbed energy (vE0) is 30 j or more and the average of the three values of the absorbed energy (vE-40) is 27 j or more is defined as steel plate having superior toughness in the contact area (in the scope of the present invention).

Regarding steel plate having a thickness of less than 10 mm, OTB�play the sample with a V-shaped incision, having reduced size (5 mm × 10 mm), and subjected to test impact strength Charpy. Steel plate, for which the mean of the three values of the absorbed energy (vE0is 15 j or more and the average of the three values of the absorbed energy (vE-40) is 13 joules or more is defined as steel plate having superior toughness in the contact area (in the scope of the present invention).

Table 5 shows the conditions of production of steel plate used in the test, and table 6 shows the results of the respective tests. In the examples of the present invention (steel No. 15-17 (steel sheet No. 17 has a thickness of 8 mm), the samples have a surface hardness of 400 HBW10/3000 or more display characteristics excellent abrasion resistance, and toughness of the base material at 0°C, equal to 30 j or more, and the toughness of the base material at -40°C, equal to 27 j or more. In addition, to test the cracking of fillet weld t-shaped profile does not have any cracks, and the samples of the present invention have excellent impact strength in relation to artificial the zone affected by the heat of welding, and real toughness of a welded joint, and therefore it is proved that the samples of this from�retenu exhibit superior impact strength of the weld.

On the other hand, it is confirmed that although the steel No. 18, which composition is in the range of the present invention, but the coefficient DI* exceeds 180, shows relevant results on the characteristics of surface hardness, abrasion resistance and impact toughness of the base material, the test results on the cracking of fillet weld t-shaped profile, the testing of artificial zone of influence of the heat of welding and testing the impact toughness for real welds are close to the lower limit of the target values, and therefore, the steel No. 18 worse than steel from other examples of the present invention according to the characteristic toughness of the weld at low temperature.

The composition of steel No. 19 on the content of the Si is beyond the scope of the present invention. Accordingly, although the steel No. 19 shows the relevant results on the characteristics of surface hardness, abrasion resistance and impact toughness of the base material deteriorates the performance impact toughness in the area of embrittlement under low temperature vacation and in the zone affected by the heat of welding, and therefore, the steel No. 19 could not meet the targets in test for cracking of fillet weld t-shaped profile, the test impact strength Charpy artificial zone of influence of heat, rela�estoya the area of embrittlement at low temperature leave and test impact strength Charpy for real welds.

Although the composition of steel No. 20 corresponds to the volume of the present invention, the parameter value calculated by the formula (2) exceeds 0,47. Accordingly, it is confirmed that the value of vE-40is close to the lower limit values of the indicator of the present invention, as in the test impact strength Charpy artificial zone of influence of heat and in the test impact strength Charpy for real welds, and therefore, the steel No. 20 worse than steel from other examples of the present invention. In the description of the tables 4, 5 and 6, although the composition of the steels Nos. 18 and 20 is in the scope of the present invention, referred to in paragraph 3, the value of the coefficient DI* and the parameter calculated by the formula (2), is outside the scope of the present invention, specified in paragraphs 6, 7, and therefore, the steel Nos. 18 and 20 are shown as comparative examples.

0,40
Table 1
No.Composition (wt.%)DI*R in the formula (2)Note
SiMnPS AlCrNbTiMoWCuNiVNInREESaMg
10,2370,300,910,0080,00150,0320,580,0160,01430Of 57.30,35An example of the present invention
20,2150,200,490,0090,0011Of 0.021 0,0240,0250,21141287,70,02An example of the present invention
30,2830,140,610,0050,00090,0380,78Of 0.0210,0090,100,150,12612364,30,23An example of the present invention
40,2230,41To 1.140007 Of 0.00160,0440,440,008Is 0.0190,042753265,10,43An example of the present invention
50,2540,260,550,0040,00080,0280,490,0120,0110,100,0562221951,90,27An example of the present invention
6016 0,321,050,0080,00210.031 inch0,590,020Is 0.0190,18451082,50,31Comparative example
70,3210,400,510,0070,00140,0250,710,0150,0120,150,210,18282074,30,28Comparative�th sample
8To 0.2630,19L430,0070,00070,0400,43Is 0.0190,0100,080,05383650At 93.20.55Comparative example
90,2740,240,950,0130,00220,0300,710,0200,0110,060,213514For 80.9Comparative example
100,2260,43Of 0.870,0080,00140,0230,140,0150,0070,2359112056,80.48Comparative example
110,2410,301,050,0060,00230,0420,600.0010,0140,110,03317 91,90,36Comparative example
120,2300,270,690,005Is 0.00100,0281,010.0390,0080,050,415384,50,12Comparative example
130,2550,210,770,0090,00140.031 inch0,470,0180.0010,14318 63,20,38Comparative example
140,2840,130,460,007With 0.00130,0510,51Of 0.0210,0105533,10,30Comparative example
Footnote 1: the Underlined values are outside of the present invention
Footnote 2: the Content of chemical components, N, In, REE, CA, Mg are indicated in ppm
Footnote 3: DI*=33,85×(0.1 x C)0,5×(0,7×Si+1)×(3,33×Mn+1)×(0,35×Cu+1)×(0,36×Ni+1)×(2,16×Cr+1)×(3×Mo+1)×(1,75×V+1)×(1,5×W+1)
Note 4: the P in the left part of formula (2)=C+Mn/4-Cr/3+10P
The numbers of the corresponding elements signify the contents (mass%)

td align="center"> 7 32
Table 2
No. steelThe thickness of the starting material (mm)Plate thickness (mm)Hot rollingThermal processingNotes
The heating temperature, °CThe final temperature of hot rolling, °CCooling methodThe heating temperature (°C)Cooling method
1200121150900cooling air900cooling waterAn example of the present invention
2200321050880cooling air900cooling waterAn example of the present invention
3200251200920cooling air930cooling waterAn example of the present invention
4200251150890cooling waterhandling missingAn example of the present invention
5200201150900cooling water200cooling airAn example of the present invention
6200251150900cooling air900cooling waterComparative example
200201150900cooling waterhandling missingComparative example
8250321200950cooling air900cooling waterComparative example
9180201100880cooling air930cooling waterComparative example
10300251150920cooling waterhandling missingComparative example
112001050870cooling air900cooling waterComparative example
12250161200900cooling waterhandling missingComparative example
11200121150860cooling air930cooling waterComparative example
14250251150900cooling air900cooling waterComparative example
Note: the Underlined values are outside of this izobreteny�

Table 3
No. steelSurface hardnessFeature abrasion resistanceThe toughness of the base materialTest cracking of fillet weld t-shaped profileTest artificial zone of influence of the heat of weldingArc metal welding with a covered electrodeNotes
HBW 10/3000Index abrasion resistancevE0(J)Heating noHeated to 100°CThe corresponding contact area (vE0(J)The corresponding region of the embrittlement at low temperature vacation vE0(J)The toughness of a welded joint vE0(J)
(the presence or absence of cracks)
1 4424,768there are no cracksthere are no cracks6048119An example of the present invention
24104,295there are no cracksthere are no cracks8370151An example of the present invention
35195,642there are no cracksthere are no cracks393377An example of the present invention
44284,585there are no cracksThere are no cracks7666128An example of the present invention
54905,057there are no cracksThere are no cracks504794An example of the present invention
63283,0168there are no cracksthere are no cracks140155182Comparative example
75986,014there are cracksthere are cracks6523Comparative example
85015,142there are cracksthere are cracks353270Comparative example
95225,437there are cracksthere are cracks28840Comparative example
104354,666there are no cracksthere are no cracks461529Comparative example
114564,725there are cracksthere are cracks201132Comparative example
124324,521there are no cracksThere are no cracks12921Comparative �reamer
134864,823there are no cracksthere are no cracks141019Comparative example
143693,542there are no cracksThere are no cracks434765Comparative example
Note: the Underlined values are outside of the present invention

Table 4
No.Composition (wt.%)DI*Formula (2)Note
SiMnPSAl CrNbTiMoWCuNiVNInREESaMg
150,2090,320,730,0060,00180,0321,050,0230,0170,173112101,40,10An example of the present invention
160,2270,270,630,0050,00200,0251,31 0,0140,0120,290,440,210,04271015178,70,00An example of the present invention
170,2160,180,600,0070,00250,0170,600,0230,0280,120,053057,00,24An example of the present invention
18Ends 0.2450,370,520,007 0,00180,0381,090,0170,0110,570,240,14301221188,60,08Comparative example
190,2760.030,930,0090,00270,0510,470,0230,0160,043050,70,44Comparative example
200,2900,27 1,080,0090,00210,0340,510,0110,0090,140,102572,00.48Comparative example
Footnote 1: the Underlined values are outside of the present invention
Footnote 2: the Content of chemical components, N, In, REE, CA, Mg are indicated in ppm
Footnote 3: DI*=33,85×(0.1 x C)0,5×(0,7×Si+1)×(3,33×Mn+1)×(0,35×Cu+1)×(0,36×Ni+1)×(2,16×Cr+1)×(3×Mo+1)×(1,75×V+1)×(1,5×W+1)
Footnote 4: the Formula (2): C+Mn/4-Cr/3+10P
The numbers of the corresponding elements signify the contents (mass%)

Thermal processing
Table 5
No. steelThe thickness of the starting material (mm)Plate thickness (mm)Hot rollingNotes
The heating temperature, °CThe final temperature of hot rolling, °CCooling methodThe heating temperature (°C)Cooling method
15250401150900cooling air900cooling waterAn example of the present invention
16300601120880cooling air870cooling waterAn example of the present invention
1720081150830cooling air900cooling waterAn example of this and�gaining
18250321100870cooling air900cooling waterComparative example
19250251100900cooling waterhandling missingComparative example
20300401150900cooling air900cooling waterComparative example
Note: the Underlined values are outside of the present invention

Table 6
No. steelSurface hardnessThe toughness of the base materialTest cracking of fillet weld t-shaped profileTest artificial zone of influence of the heat of weldingArc metal welding with a covered electrodeNotes
HBW 10/3000Index abrasion resistancevE0(J)vE-40(J)Heating noHeated to 100°CCorresponding contact sectionThe corresponding region of the embrittlement at low temperature vacationThe impact strength of the multilayer weld
(the presence or absence of cracks)vE0(J)vE-40(J)
vE0(J)vE-40(J)vE-40(J)
154114,28366there are no cracksthere are no cracks90617246133105An example of the present invention
164354,77049there are no cracksthere are no cracks654059388350An example of the present invention
174154,34833there are no cracksthere are no cracks43283830 6539An example of the present invention
184824,75036there are no cracksthere are no cracks362830273527Comparative example
195285,53524there are cracksthere are cracks31232192814Comparative example
205465,83834there are no cracksthere are no cracks332830 273527Comparative example
Note: the Underlined values are outside the present invention.

1. Abrasion resistant steel plate having a composition containing, in wt.%: from 0.20 to 0.30 C, from 0.05 to 1.0 Si, 0.40 to 1.2 MP, from 0.010 or less P, 0.005 or less of S, from 0.40 to 1.5 Cr, from 0.005 to 0.025 Nb, 0.005 to 0.03 Ti, 0.1 or less Al, 0.01 or less N, and the rest Fe and inevitable impurities, in which the hardening coefficient DI* defined by the expression (1):
DI*=33,85×(0.1 X C)0.5×(0,7×Si+l)×(3,33×Mn+l)×(0,35×Cu+l)×(0,36×Ni+l)×(2,16×Cr+l)×(3×Mo+1)×(l,75×V+l)×(l,5×W+l) (1),
is 45 or greater, where C, Si, Mn, Cu, Ni, Cr, Mo, V and W denote concentration in the steel of these elements in wt.%, wherein the steel has a microstructure, the main phase of which is formed of martensite particles and carbonitride of Nb and Ti having an average particle size of 1 μm or less are present in quantities of 1000 pieces/mm2or more, and the average particle size of prior austenite is less than 200 microns.

2. Steel according to claim 1, characterized in that it further comprises, in wt.%: one, two, or more components selected from the group consisting of: from 0.05 to 1.0 Mo, from 0.05 to 1.0 W and from 0,0003 to 0,0030 V.

3. Steel according to claim 1, characterized in that it further comprises, in wt.% one two or more components selected from the group consisting of 1.5 or less Cu, 2.0 or less Ni, and 0.1 or less than V.

4. Steel according to claim 2, characterized in that it further comprises, in wt.%: one, two, or more components selected from the group consisting of 1.5 or less Cu, 2.0 or less Ni, and 0.1 or less than V.

5. Steel according to any one of claims. 1-4, characterized in that it further comprises, in wt.%: one, two, or more components selected from the group consisting of 0.008 or less of rare earth elements (REE), 0.005 or less of CA and 0.005 Mg or less.

6. Steel according to any one of claims. 1-4, characterized in that it has a surface hardness equal to 400 HB W10/3000 or more on a scale of hardness Brinell.

7. Steel according to claim 5, characterized in that it has a surface hardness equal to 400 HB W10/3000 or more on a scale of hardness Brinell.

8. Steel according to any one of claims. 1-4 or 7, characterized in that the hardening coefficient DI* is 180 or less.

9. Steel according to claim 5, characterized in that the hardening coefficient DI* is 180 or less.

10. Steel according to claim 6, characterized in that the hardening coefficient DI* is 180 or less.

11. Steel according to any one of claims. 1-4, 7, 9 or 10, characterized in that the content of components corresponds to the expression (2):
C+Mn/4-Cr/3+10P≤0,47 (2),
where C, Mn, Cr and P denote concentration of these elements in wt.%.

p> 12. Steel according to claim 5, characterized in that the content of components corresponds to the expression (2):
C+Mn/4-Cr/3+10P≤0,47 (2),
where C, Mn, Cr and P denote concentration of these elements in wt.%.

13. Steel according to claim 6, characterized in that the content of components corresponds to the expression (2):
C+Mn/4-Cr/3+10P≤0,47 (2),
where C, Mn, Cr and P denote concentration of these elements in wt.%.

14. Steel according to claim 8, characterized in that the content of components corresponds to the expression (2):
C+Mn/4-Cr/3+10P≤0,47 (2),
where C, Mn, Cr and P denote concentration of these elements in wt.%.



 

Same patents:

FIELD: metallurgy.

SUBSTANCE: steel for antifriction casting contains the following elements, wt %: carbon 1.3-1.5; silicon 0.3-0.4; manganese 0.2-0.6; copper 3.0-10.0; chromium 0.06-0.1; aluminium 0.5-2.0; titanium 0.05-2.0, stannum 0.02-0.1; calcium 0.002-0.005; iron - the rest.

EFFECT: improved service life of part in the friction pair, no need in heat treatment of castings, improved conditions of castings calcium to parts.

2 tbl

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to production of stainless steel sheet for fuel element separator. Sheet is made of steel containing in wt %: C: 0.05-0.20%, Si: 0.10% or less, Mn: 0.2-1.7%, P: 0.10% or less, S: 0.10% or less, Al: 0.01-0.10%, N: 0.010%, Fe and arbitrarily impurities making the rest.Si: 1.0 or less, Mn: 1.0 or less, S: 0.01 or less, P: 0.05 or, Al: 0.20 or less, N: 0.03 or less, Cr: 20-40, at least one of metals selected from the group including Nb, Ti and Zr, on the whole: 1.0 or less, Fe unavoidable impurities making the rest. Coating is applied on sheet surface and that features the relationship of definite methods of X-ray photo electronic spectroscopy intensities [(OO/OH)/(Cr/Fe)], equal to 1.0 or larger. Said coating is formed by anodic polarisation of stainless steel surface in electrolyte solution with sodium sulphate concentration of 0.1-0.3 mol/l and pH of 7 or less at potential of 0.5 V or higher relative to standard hydrogen electrode for 10 seconds or more.

EFFECT: higher corrosion resistance.

15 cl, 1 dwg, 7 tbl, 5 ex

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to production of stainless steel sheet for fuel element separator. Said steel contains the following substances, in wt %: C: 001 or less, Si: 1.0 or less, Mn: 1.0 or less, S: 0.01 or less, P: 0.05 or less, Al: 0.20 or less, N: 0.02 or less, Cr: 20-40, Mo: 4.0 or less and at least one element selected from Nb, Ti, and Zr: 0.05-0.60 on the whole, Fe and unavoidable impurities making the rest. Cold-rolled sheet 200 mcm in depth or less is cooled at cooling rate adjustment R (°C/c) depending upon steel sheet depth t (mcm) to at least 500°C after annealing so that cooling rate R satisfies the formula: -17,27×ln(t)+92≤R≤70; per 100 mcm2 at least island exists with equivalent circle diameter of 0.1 mcm of larger while sheet depth t (mcm) to-maximum diameter Dmax of said island satisfies the following formula: 20≤t/Dmax.

EFFECT: high conductance and plasticity.

2 cl, 2 dwg, 2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: continuous cast steel billets of certain chemical composition are produced; their austenisation is performed at the temperature of 1180-1210°C; then, roughing-down is performed at the temperature of 940-1180°C with reduction of cross-sectional areas per pass of not less than 12%, air cooling of deformed billet to the temperature of 720-780°C is performed, finish rolling is performed at the temperature interval of 750-790°C with total reduction of cross-sectional area of 50-60% and accelerated cooling of a finished rolled metal is performed at temperature interval of 730-770°C to 580-620°C with cooling rate of 15-20°C/sec.

EFFECT: development of a 60-90 mm thick rolled metal production technology with guaranteed yield point of not less than 275 MPa and increased impact strength.

2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: steel contains the following, wt %: C about 0.015 or less, Si from about 0.4 to 1.0, Mn about 1.0 or less, P about 0.040 or less, S about 0.010 or less, Cr from about 16 to 23, Al from about 0.2 to 1.0, N about 0.015 or less, Cu from about 1.0 to 2.5, Nb from about 0.3 to 0.65, Ti about 0.5 or less, Mo about 0.1 or less, W about 0.1 or less, Fe and unpreventable impurities the rest. Si and Al content satisfies the ratio Si (wt %) ≥ Al (wt %).

EFFECT: steel has high oxidation stability, thermal fatigue indices and fatigue at high temperatures.

7 cl, 10 dwg, 2 tbl, 2 ex

FIELD: metallurgy.

SUBSTANCE: in the obtained hot-rolled sheets of the selected chemical composition of steel is reached via temperature regulation of hot rolling crude stage within 980÷1100°C with semi-finished rolled product thickness for finishing stage 140÷170 mm, the beginning of rolling finishing stage within 780÷820°C and the end of hot rolling 780÷810°C. Moreover the temperature of sheet accelerated cooling end is taken 560÷600°C.

EFFECT: provision of tube range 26-28 mm thick in hot-rolled products from micro-alloyed steel with equal mechanical properties by sheet section corresponding to X60 strength grade.

1 ex, 1 tbl

Steel // 2445395

FIELD: metallurgy.

SUBSTANCE: steel contains the following, wt %: carbon 0.1-0.15; silicium 0.3-0.5; manganese 0.2-0.4; chrome 5.0-6.0; yttrium 0.15-0.25; copper 2.2-2.8; calcium 0.003-0.005; zirconium 0.1-0.15; beryllium 0.01-0.02; boron 0.1-0.15; iron- the rest.

EFFECT: increasing steel strength.

1 cl, 1 tbl

Die steel // 2445394

FIELD: metallurgy.

SUBSTANCE: die steel contains the following, wt %: carbon 0.1-0.13; silicium 0.001-0.002; manganese 0.05-0.1; chrome 0.05-0.1; molybdenum 0.3-0.4; tungsten 0.1-0.2; vanadium 0.2-0.3; aluminium 0.01-0.02; titanium 0.01-0.02; cobalt 17.0-19.0; zirconium 0.3-0.4; nickel 17.0-19.0; samarium 0.2-0.3; iron is the rest.

EFFECT: increasing steel impact strength.

1 tbl

FIELD: metallurgy.

SUBSTANCE: steel contains the following, wt %: carbon 0.015 or less, silicium 0.5 or less, manganese 0.5 or less, phosphorus 0.04 or less, sulphur 0.006 or less, chrome 16 to 20, nitrogen 0.015 or less, niobium 0.3 to 0.55, titanium 0.01 or less, molybdenum 0.1 or less, tungsten 0.1 or less, copper 1.0 to 2.5, aluminium 0.2 to 1.2, iron and inevitable impurities are the rest. Steel can also contain one or several components chosen from boron 0.003 wt % or less, rare-earth metals: 0.08 wt % or less, zirconium 0.5 wt % or less, vanadium 0.5 wt % or less, cobalt 0.5 wt % or less and nickel 0.5 wt % or less.

EFFECT: steel has excellent thermal fatigue resistance, excellent oxidation resistance and high viscosity.

2 cl, 9 dwg, 2 tbl, 2 ex

FIELD: metallurgy.

SUBSTANCE: steel contains carbon, silicon, manganese, chromium, molybdenum, vanadium, niobium, titanium, nickel, copper, aluminium, calcium, sulphur, phosphorus, hydrogen, oxygen and iron at following ratio of components, wt %: carbon 0.14 - 0.23, silicon 0.14 - 0.40, manganese 0.50 - 0.90, chromium 2.0 - 3.0, molybdenum 0.10 - 0.30, vanadium 0.05 0.17, niobium 0.02 - 0.08, titanium 0.005 - 0.030, aluminium 0.020 - 0.050, calcium 0.0010 - 0.0030, nickel not over 0.30, copper not over 0.30, sulphur not over 0.010, phosphorus not over 0.015, oxygen not over 20 ppm, hydrogen not over 2 ppm, iron - the rest. Chromium equivalent of steel meets the condition Crequiv>3.0, where Crequiv=[Cr]+2·[Mo]+5·[V]+1.5[Nb]+1.5[Ti].

EFFECT: raised corrosion resistance of pipes for wells with mediums saturated with acid gases at ratio without decrease of cold resistance and strength characteristics.

5 tbl, 1 ex

Rail steel // 2259416

FIELD: ferrous metallurgy; production of rail steel.

SUBSTANCE: the invention is pertaining to the field of ferrous metallurgy, in particular, to production of steel for manufacture of railway rails. The offered rail steel contains its components in the following ratio (in mass %): Carbon - 0.83-0.5; manganese - 0.6-1.1; silicon - 0.3-0.7; vanadium - 0.08-0.15; aluminum - no more than 0.005; nitrogen - 0.012-0.02; calcium -0.0005-0.005; chromium - 0.05-0.5; one of the devices sampled from a group including zirconium and REM, namely, zirconium -0.0005-0.005; REM - 0.0005-0.005; molybdenum - 0.11-0.3; nickel - 0.05-0.3, iron and impurities - the rest. The technical result of the invention is an increased complex of mechanical properties, firmness of steel and its resistance to brittle fracture, which improves operational stability of the rails. Out of the steel of a stated composition it is possible to manufacture the rails hardened both in oil and in a compressed air with a troostite structure.

EFFECT: the invention ensures an increased complex of the rail steel mechanical properties, firmness of the steel, its resistance to brittle fracture and production of rails with a troostite structure.

2 tbl

FIELD: metallurgy; production of round merchant shapes made from medium-carbon steel of enhanced machinability for manufacture of automobile shock absorber rods.

SUBSTANCE: steel used for manufacture of round bars contains the following components, mass-%: carbon, 0.40-0.52; manganese, 0.40-0.95; silicon, 0.17-37; chromium, 0.01-0.25; sulfur,0.020-0.045; vanadium, 0.005-0.02; aluminum, 0.03-0.05; calcium, 0.001-0.010; nitrogen, 0.005-0.015; nickel, no more than 0.25%; copper, no more than 0.25; molybdenum, no more than 0.10; arsenic, no more than 0.08; phosphorus, no more than 0.030; the remainder being iron and unavoidable admixtures at calcium-to-sulfur ratio ≥0.065. Nonmetallic inclusions of sulfides have double layer structure: sulfide with envelope. Curvature of bars does not exceed 0.5 mm/m. Shapes have laminated ferrito-pearlite structure at actual size of grain of 5-8 points; diameter of bars ranges from 10 to 300 mm; it has no decarbonized layer; hardness of billet is 229-255; rupture strength is no less than 660 Mpa; relative elongation is no less than 8% and relative reduction of area is no less than 35%.

EFFECT: improved ductility characteristics; low level of strain hardening at further heat treatment.

1 ex

Steel // 2311482

FIELD: ferrous metallurgy; composition of steels used in mechanical engineering and light and automobile industries; farming and tractor engineering.

SUBSTANCE: proposed steel contains the following constituents, mass-%: carbon, 0.1-0.02; silicon, 0.05-0.1; manganese, 0.1-0.3; chromium, 10.0-14.0; aluminum, 0.06-0.1; molybdenum, 0.5-1.5; magnesium, 0.03-0.08; nickel, 12.0-16.0; titanium, 0.20.4; the remainder being iron.

EFFECT: increase of work in development of cracks.

1 tbl

Steel // 2311483

FIELD: ferrous metallurgy; composition of chromium steels used for manufacture of parts for thermal units, engines, hot deformation tools and other articles.

SUBSTANCE: proposed steel contains the following constituents, mass-%: carbon, 1.2-1.6; silicon, 1.2-1.4; manganese, 0.6-1.0; chromium, 10.0-12.0; vanadium, 1.2-1.6; molybdenum, 5.0-6.0; tungsten, 1.0-2.0; titanium, 0.2-0.4; zirconium, 0.1-0.2; hafnium, 5.0-6.0; calcium, 0.003-0.005; the remainder being iron.

EFFECT: enhanced heat resistance of steel.

1 tbl

Steel // 2314359

FIELD: ferrous metallurgy; steels used in mechanical engineering.

SUBSTANCE: proposed steel contains the following constituents, mass-%: carbon, 0.5-0.7; silicon, 0.05-0.15; manganese, 0.6-1.0; aluminum, 0.08-0.12; titanium, 0.6-1.0; chromium, 3.0-4.0; copper, 0.6-1.0; the remainder being iron.

EFFECT: enhanced hardness; reduced cleavability of steel.

1 tbl

Steel // 2314360

FIELD: ferrous metallurgy; steels used in mechanical engineering.

SUBSTANCE: proposed steel contains the following constituents, mass-%: carbon, 0.1-0.15; silicon, 0.2-0.4; manganese, 0.3-0.8; chromium, 5.0-6.0; copper, 0.6-1.0; calcium, 0.003-0.005; zirconium, 1.0-1.5; vanadium, 2.5-3.5; aluminum, 0.05-0.15; the remainder being iron.

EFFECT: enhanced strength of steel.

1 tbl

FIELD: metallurgy; ferrous.

SUBSTANCE: said utility invention relates to the field of steel metallurgy. It may be used in the nuclear power industry, in particular, for producing components of nuclear slow-neutron water-cooled reactor cores. The steel contains the following components, % weight: carbon 0.15-0.20; silicon 1.3-1.7; manganese 1.0-2.0; chromium 13.0-15.0; tungsten 0.6-0.8; vanadium 0.1-0.3; titanium 0.1-0.3; cerium and/or yttrium total 0.001-0.100; zirconium 0.1-0.3; nitrogen 0.02-0.15; iron and inevitable impurities being the remaining. The ratio of the total contents of vanadium, zirconium, and titanium the total contents of carbon and nitrogen is 1.5 to 5.0. The total contents of chromium and silicon is 14.3-16.0 % weight. The produced steel has a low level of induced radiation, its faster decay after a neutron exposure while maintaining a high level of embrittlement resistance at 280-350 °C under neutron radiation, and a high level of corrosion resistance in water and steam at the said temperatures, with a service life of up to 30-40 years.

EFFECT: production of steel with low level of induced radiation, maintaining properties under neutron radiation and in high-temperature liquid or steam, with increased service life.

5 cl, 4 tbl, 1 ex

Steel // 2331701

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy and can be used for fabrication of pipes, reservoirs and tanks. Steel contains, mass.%: carbon 0.4-0.8; silicon 0.4-0.8, manganese 0.4-0.8; chromium 1.0-2.0; aluminium 0.1-0.2; titanium 0.1-0.2; nitrogen 0.02-0.04; arsenic 0.003-0.005; niobium 0.4-0.8; molybdenum 3.5-4.5; beryllium 0.003-0.005; iron constitutes the remaining percentage.

EFFECT: upgraded hardness of steel.

1 tbl

FIELD: metallurgy.

SUBSTANCE: invention concerns belts manufacturing from hot-rolled high-strength steel of bainitic-martensitic composition with content up to 5% of ferrite. In hot condition it is rolled at temperature less than 950°C slab, comprising carbon, manganese, chrome, silicon, titanium, aluminium, sulphur, phosphorus, iron and foundry admixtures, at following components ratio, mass% 0.05≤C≤0.1, 0.7≤Mn≤1.1, 0.5≤Cr≤1.0, 0.05≤Si≤0.3, 0.05≤Ti≤0.1, Al≤0.07, S≤0.03, P≤0.05, iron and foundry admixtures are the rest. Received band is cooled till temperature which is less or equal 400°C while cooling rate over 50°C/c in the range 800 - 700°C and reeled at temperature which is less or equal 250°C.

EFFECT: improving of endurance and blow resistance of hot-rolled high-strength steel.

20 cl, 1 ex

Steel // 2334817

FIELD: metallurgy.

SUBSTANCE: invention refers to iron and steel industry and can be implemented for fabrication of punches, and die molds for casting of brass. Steel contains, mass %: carbon 0.2-0.3; silicon 0.2-0.3; manganese 1.2-1.4; chromium 2.0-3.5; vanadium 0.6-0.8; titanium 0.08-1.0; molybdenum 1.2-1.4; niobium 0.08-0.12; copper 0.1-0.3; cerium 0.8-1.0; lanthanum carbide 0.05-1.0; zirconium boride 0.2-0.3; aluminium 0.01-0.02; beryllium carbide 0.8-1.2; iron - the rest. Hardness of steel (HRC) at temperature of 600°C is 52-54, bearing resistance is 0.1-0.12 mm.

EFFECT: upgraded hardness and bearing resistance of steel.

2 tbl

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