Cold-rolled steel plate with excellent formability and its manufacturing method

FIELD: metallurgy.

SUBSTANCE: invention refers to metallurgy. In order to achieve the technical result, a plate is made from steel containing the following components, wt %: C 0.010 to 0.035 (excluding 0.010%), Si 0.1 or less, Mn 0.35 or less, P 0.035 or less, S 0.02 or less, N 0.0060 or less, Al 0.005 to 0.1, Fe and inevitable impurities are the rest provided that [% Mn]/[% Al]<20, where [% M] represents content (wt %) in steel of element M, with that, diameter of ferrite grain in steel does not exceed 5 mcm, and at least 50% of separated cementite is within boundaries of ferrite grains.

EFFECT: production of a cold-rolled steel plate with stable increased formability.

9 cl, 2 tbl, 1 ex

 

The technical field to which the invention relates.

The present invention relates to a cold rolled steel sheet having excellent formability, suitable as a material for structural components used in automobiles, buildings, furniture, instrument panels, consumer electronics, etc. of the Present invention also relates to a method of producing such a cold-rolled steel sheet.

The level of technology

Due to good formemost cold-rolled steel sheets are used as a material for various construction elements. Typically, steel sheet, which is a two-dimensional object, is converted by pressing in a three-dimensional structure, and then the thus obtained three-dimensional structure welded together in more complex designs. Accordingly, the cold-rolled steel sheet must have a good formability.

With regard to the above-described cold-rolled steel sheet JP-A 61-124533 discloses a method of manufacturing cold-rolled steel sheet that is excellent in terms of formemost and resistance to aging by reducing the content of C, Mn, Al and N, perform cold rolling with a degree of compression of at least 50% and subsequent annealing with job specific cooling conditions, pelestarian what I'm after annealing, and also a job a certain degree of compression when training.

However, although the resulting steel sheet has a relatively good resistance to aging, the method of JP-A 61-124533 has the disadvantage that is associated with the mandatory need for a high degree of compression during training, which significantly deteriorates the formability of the steel sheet.

JP-A 02-267227 discloses a production method having good formability of cold rolled steel sheet through a set of indicators content in steel, Mn, S, O and b, continuous casting of steel under certain unique conditions, hot rolling, cold rolling and continuous annealing, in that order.

However, the method of JP-A 02-267227 has the disadvantage associated with the fact that in order to ensure control of the size of MnS, through the formation of large amount of oxide inclusions, the oxygen content of the steel should be at least 60 hours/million, despite the fact that these oxide inclusions cause the stamping process cracking.

JP-A 07-216459 discloses a technology for the production of cold-rolled steel sheet having excellent performance as aging resistance and formemost due to job specific quantities of content in the steel C, Si, Mn, P, Al and N of hot rolled steel, cold rolling and continuous annealing in the specified n is the row, so that during continuous annealing, the steel is rapidly heated and rapidly cooled.

However, the method of JP-A 07-216459 has the disadvantage that the heat cannot uniformly be spread throughout the area of steel, so that the formability of the obtained steel sheet is improved only partially.

The invention

The problem addressed by the invention

As described above, stable from the point of view of industrial applications creating cold-rolled steel sheet having good formability, using conventional methods is difficult. The present invention is directed to an effective solution to the aforementioned problems of the prior art, and its objective is to create a cold-rolled steel sheet, consistently demonstrating good formability, and preferred method of producing such a cold-rolled steel sheet.

Solutions to problems

Formability of cold rolled steel sheet usually improved mainly by the reduction of dissolved in carbon steel and, as an aid in optimizing conditions perestiani and training in the manufacturing process of the steel sheet.

But now comes a shared understanding of the difficulties to further improve formemost cold what about the steel sheet using this approach, as described above, that is, relying mainly on the reduction of dissolved in carbon steel.

Given this situation, the authors of the present invention researched and other factors affecting the improvement of formemost steel sheet, in addition to simply reducing the content of dissolved carbon (in particular, elongation) and as a result discovered that in order to improve formemost steel sheet, it is necessary to control the diameter of ferrite grains, the localization of cementite, and the content of dissolved carbon; steel composition having a relatively low content of Mn, the preferred regarding the proper management of the diameter of ferrite grains and localization of cementite; the content of Mn as forming austenite element to the content of Al as an element forming the ferrite, must be within a certain range to ensure the proper management of the diameter of ferrite grains, the localization of cementite, etc.

The present invention was accomplished based on the above discoveries, and its main characteristics are the following.

(1) cold-Rolled steel sheet having excellent formability containing composition, comprising in mass percent:

From: 0,010% to 0.035% of (excluding 0,010%);

Si: 01% or less;

MP: 0,35% or less;

P: 0,035% or less;

S: 0,02% or less;

N: 0,0060% or less;

Al: 0.005 to 0.1%;

and Fe and incidental impurities - the rest,

in which the ratio [% MP]/[% Al]<20, where [% M] represents the content in the steel of the element M in wt.%; the diameter of the ferrite grains in the steel does not exceed 5 microns; and at least 50% of cementite is located on the borders of ferritic grains.

(2) Having excellent formability of cold rolled steel sheet according to the above item (1), the composition of which includes, in addition, in mass% 0,0035% or less of the Century

(3) Having excellent formability of cold rolled steel sheet according to the above paragraphs (1) or (2), the composition of which includes, in addition, at least one element selected from the group consisting of si, Sn, Ni, Ca, Mg, Co, As, Cr, Mo, Sb, W, Nb, Ti, Pb, TA, REM (rare earth metals), V, Cs, Zr and Hf, so that their total content in the steel is the mass percentage of 1% or less.

(4) Having excellent formability of cold rolled steel sheet according to any of the above items (1)to(3), the surface of which is coated with the coating layer.

(5) the production Method having excellent formability of cold rolled steel sheet containing stage: preparation of steel material having a composition of components according to l is the Boma of the above paragraphs (1)-(3); hot rolling, including the finishing rolling steel material, to obtain a steel sheet; and after finishing the winding roll steel sheet, pickling, cold rolling, continuous annealing and perezharivaya processing specified in a different order:

by heating the steel material during hot rolling to a temperature of the single-phase region of austenite and the completion of hot rolling at a temperature of finish rolling is in the range from 820°C to 930°C (including 820°C and excluding 930°C);

perform winding into a roll at a temperature in the range from 540°C to 740°C (including 540°C and excluding 740°C);

removing scale from the surfaces of the steel sheet by pickling;

performing cold rolling with a degree of compression of at least 55%;

by carrying out annealing at a heating temperature during annealing is equal to or higher than 680°C;

cooling the annealed thus the steel sheet from 680°C to temperature perestiani when the cooling rate is at least 20°C./sec; and

holding perezharivaya processing at a temperature equal to or greater than 360°C.

(6) the production Method having excellent formability of cold rolled steel sheet containing stage: preparation of steel material having a composition of components according to any of the above paragraphs (1)-(3); hot about is atki steel material, including finishing rolling, to obtain a steel sheet; and after finishing the winding roll steel sheet, pickling, cold rolling and annealing in containers specified in a different order:

by heating the steel material during hot rolling to a temperature of the single-phase region of austenite and the completion of hot rolling at a temperature of finish rolling is in the range from 820°C to 930°C (including 820°C and excluding 930°C);

perform winding into a roll at a temperature in the range from 540°C to 740°C (including 540°C and excluding 740°C);

removing scale from the surfaces of the steel sheet by pickling;

performing cold rolling with a degree of compression of at least 55%; and

by carrying out annealing in containers at the heating temperature during annealing in the range from 600°C to 750°C (including 600°C and 750°C).

(7) the production Method having excellent formability of cold rolled steel sheet according to the above paragraphs (5) or (6), containing, in addition, the coating on the steel sheet after perezharivaya processing or annealing in containers.

The effect of the invention

According to the present invention it becomes possible to create a cold-rolled steel sheet, consistently demonstrating good formability, and creating an efficient method of manufacturing such a cold-rolled with the material of the sheet.

The implementation of the invention

Hereinafter the present invention will be described in more detail.

Cold-rolled steel sheet having excellent formability.

First of all, there will be explained the reasons why the composition of the components of the cold-rolled steel sheet is limited in the present invention the above ranges. In the present invention metrics "%" and "h/m" the following compositions components represent, respectively, the mass percent mass ratio of parts per million, unless stated otherwise.

From: 0,010% to 0.035% of (excluding 0,010%).

Carbon exists in the steel or in the form of cementite, or in a state dissolved carbon. The carbon content in steel 0,010% or less reduces the driving force for precipitation of dissolved carbon, thus complicating the deposition of carbon in the form of cementite. Accordingly, the carbon content of the steel should not exceed 0,010% and is preferably at least 0.015 percent.

However, the carbon content in steel exceeding 0.035%of leads to a too high content of cementite, increasing, thus, the number of lots of the formation of pores that appear on the border between cementite and ferrite in the stamping process and thereby deteriorating the elongation of the steel sheet. Accordingly, the carbon content of the steel should the be a 0.035% or less, preferably of 0.03% or less and more preferably 0.025% of range or less.

Si: 0.1% or less.

Silicon is an element, which prevents the formation of cementite, inhibiting the transformation of cementite carbides. The content of silicon steel, exceeding 0.1%, may cause a situation in which cementite is not allocated in appropriate positions, which may contribute to the formation of cementite in a ferrite matrix. Accordingly, the Si content in the steel should be 0.1% or less and preferably 0.05% or less.

Mn: 0,35% or less.

Manganese, although not react with carbon to form compounds, physically interacts with carbon steel; suppressing uniform diffusion of carbon, thus ultimately preventing the formation of cementite at the grain boundaries and impairing the formability of the obtained steel sheet. Accordingly, the Mn content, and the content of Si in the present invention preferably reduced. More specifically, the content of Mn in the steel should be present in the invention of 0.35% or less, and preferably of 0.30% or less.

P: 0,035% or less.

Phosphorus due to its segregation at the boundaries of ferritic grain, prevents deposition on the boundaries of ferrite grains of cementite and thus deteriorates the formability of the steel sheet. Accordingly, the phosphorus content in the steel should be a 0.035% or less, and predpochtitelno 0,030% or less.

S: 0,02% or less.

Sulfur in the present invention is an element that is attached to the Mn with the formation of MnS. Too much sulfur in the steel leads to the formation of excessive amounts of MnS, which slows the growth of ferrite grains, leads to a decrease in the size of ferritic grains and, thus, degrades the formability of the obtained steel sheet. Accordingly, the content of sulfur in the steel should be in the present invention is 0.02% or less and preferably of 0.015% or less.

N: 0,0060% or less.

Nitrogen is associated with aluminum, with the formation of AlN, and in cases when added to steel boron, connects with boron with the formation of BN. Therefore, too high content of nitrogen in steel leads to the formation of excessive amounts of nitride, thereby disrupting the uniformity of the grain growth of ferrite, reducing the size of ferritic grains and thus impairing the formability of the obtained steel sheet. Accordingly, the nitrogen content of the steel should be in the present invention 0,0060% or less and preferably 0,0045% or less.

Al: 0.005% to 0.1%.

Aluminum is an important element for the present invention. Although aluminum does not react with carbon to form carbide, aluminum removes carbon from the ferritic matrix and promotes the formation of cementite at the boundaries of ferrite grains. For the stijene this effect and, thus, sufficient improvement of formemost obtained steel sheet is necessary that the Al content in the steel was at least 0,005% and preferably at least 0.01 percent. However, the content in steel Al, exceeding 0.1%, leads to the formation of fine AlN and the reaction of aluminum with oxygen - fine aluminum oxide in the form of random impurities, thereby reducing the size of ferritic grains. Accordingly, the Al content in the steel should be 0.1% or less.

In addition to the above essential components, the composition of the steel sheet of the present invention may also, depending on the need to include the elements described below.

In: 0,0035% or less.

In the cases where the composition of the boron is added, it binds to the nitrogen with the formation of BN and consequently suppresses the precipitation of finely dispersed AlN. In addition, when the deposition of BN includes MnS as embryos and thus reduces the quantity of steel fine MnS. Because of this boron promotes the growth of ferrite grains.

However, the boron content in steel exceeding 0,0035%, leads to segregation of excess boron on the boundaries of ferrite grains, which dissolved boron slows the deposition on the borders of the ferritic grain carbide, and the formability of the obtained steel sheet uhudshaet is. Accordingly, the content of boron to steel should be 0,0035% or less.

At least one element selected from the group consisting of Cu, Sn, Ni, CA, Mg, Co, As, Cr, Sb, W, Mo, Pb, TA, REM, Ti, Nb, V, Cs, Zr and Hf, when the total content of 1% or less.

Cu, Sn, Ni, CA, Mg, Co, As, Cr, Sb, W, Mo, Pb, TA, REM, Ti, Nb, V, Cs, Zr, and Hf, respectively, are elements that are useful for improving corrosion resistance of steel. However, the total content of these elements in steel exceeding 1%, leads to their segregation at the grain boundaries, thereby suppressing the precipitation on the grain boundaries of cementite. Accordingly, as in the case of individual add these elements, and in the case of adding in the form of combinations, their total content in steel is to be 1% or less and preferably 0.5% or less.

It should be noted that the remaining part or components of the composition of the steel sheet, in addition to the above, presents Fe and incidental impurities.

However, a simple regulation of the compositions of the components of the steel sheet of the present invention to the above-mentioned ranges to achieve the desired in the present invention the effect is not enough. Critical in the present invention is properly controlled quantities of the relationship of the content of the MP to the contents of Al, the diameter of the ferrite grains and the fraction released at the boundaries of the ferrite is s grains of cementite, respectively.

More specifically, in the present invention it is essential that the ratio [% MP]/[% Al]<20, where [% M] represents the content in the steel of the element M in wt.%; the diameter of the ferrite grains in the steel does not exceed 5 microns; and at least 50% spin-off of cementite is located on the borders of ferritic grains.

[% MP]/[% Al]<20, where [% M] represents the content in the steel of the element M, wt.%.

This is a very important requirement to the components in the present invention.

Manganese is an element involved in the formation of austenite. In addition, the CHM physically interacts with the carbon in the steel, preventing uniform diffusion of carbon and thus inhibiting the precipitation of cementite at the boundaries of ferrite grains. In addition, the MP itself is dissolved in the cementite, making it more fine. On the other hand, aluminum is forming the ferrite element and slows down the formation of cementite in a ferrite matrix. Considering these facts, the content of aluminum in the steel in the present invention is controlled to eliminate the above-mentioned effects Mn.

More specifically, [% MP]/[% Al]>20 increases above the called Mn effects and can lead to situations in which cementite is not deposited in the proper positions, thereby impairing the formability of the obtained steel sheet. Accordingly, the value of [% MP]/[% Al] should be m is Nise 20. However, too small values [% MP]/[% Al] trends contribute to the coarsening of cementite with precipitation at grain boundaries of coarse spherical cementite and, thus, reduce the elongation of the steel sheet. Accordingly, the value of [% MP]/[% Al] is preferably at least 1, although this lower limit in a special way scope of the present invention does not limit.

The diameter of ferrite grains: at least 5 microns.

The diameter of the ferrite grains is less than 5 μm resulted in a relatively high yield strength and reduces elongation, thus impairing the formability of the steel sheet. Accordingly, in the present invention the diameter of the ferrite grains in the steel should be at least 5 μm. However, the diameter of ferrite grains exceeding 30 μm, leads to the formation on the surfaces of the steel sheet when it is subjected to molding, significant irregularities (referred to as "orange peel"), which degrades formability and quality appearance of the steel sheet. Accordingly, in the present invention the diameter of the ferrite grains in the steel should be at least 30 microns.

Precipitation of cementite: at least 50% must be submitted at the boundaries of ferrite grains.

The proportion of cementite released at the boundaries of ferrite grains are important for the present izaberete the Oia. Cementite precipitated at the boundaries of ferrite grains in sufficient quantities, effectively diminishes fine cementite present in the ferritic matrix, and contributes to the deformation of ferritic grains. In cases when the share of sudivshegosya at the boundaries of ferrite grains of cementite is less than 50%, the deformation of ferrite is suppressed by the presence of fine cementite within the ferritic grains and the formability of the obtained steel sheet is degraded. Accordingly, at least 50% of the emitted phase cementite should the present invention be located at the boundaries of ferrite grains.

The proportion of cementite released at the boundaries of ferrite grains of the steel, can be determined from the transverse steel structure by making the cross section of the steel sheet in the thickness direction of the sheet, cut parallel to the rolling direction for consideration of its structure; polishing the cross-section to a mirror finish; the identification of cementite by etching petrolem; consideration shown thus of cementite under the scanning electron microscope (×1000); and the determination of the relationship of the area of cementite presented on the boundaries of ferrite grains to the total area of cementite is the ratio of the areas is considered as "the proportion of cementite, the cent is amagosa on the borders of ferritic grains".

Steel sheet of the present invention may have on its surface a coating layer or a cladding film. The coating layer formed on the surface of cold-rolled steel sheet, improves corrosion resistance cold rolled steel sheet. Examples of coatings (layers) include zinc coating, annealed zinc coating, the coating applied by the method of electrolytic galvanizing in the melt, electrolytic plating such as electrolytic plating of Nickel-zinc alloy, etc.

Method of manufacturing cold-rolled steel sheet having excellent formability.

The following describes the method of manufacturing cold-rolled steel sheet of the present invention.

In the present invention, cold-rolled steel sheet is produced by preparing a steel material, such as preferably obtained by continuous casting slab; exposure of this steel material hot rolling, including the finishing rolling, to obtain a steel sheet; and exposure of this steel sheet after finish rolling, cooling, winding into a roll, pickling, cold rolling, continuous annealing or annealing in containers and perezharivaya processed in the specified order.

In the present invention a method of manufacturing an ingot steel materialistically not limited and suitably may be any known method of preparing metal ingots, such as cooking using a Converter, electric furnace, induction furnace, etc. casting Method is also not specifically limited. Properly can be applied to continuous casting. In regard to the hot rolling of the slab, the slab may be hot rolled or after reheating the slab heating furnace, or after a short-term heating in the heating furnace for the purpose of temperature compensation.

Thus obtained steel material is subjected to hot rolling. Hot rolling may include rough rolling and finish rolling, or consist only of finish rolling, skipping the stage of the roughing rolling. In any case, the temperature of the heating of the slab and the temperature of the finish rolling is critical.

The temperature of the heating slab: within the temperature range corresponding to the single-phase region of austenite.

Setting the heating temperature of the slab in the two-phase region of ferrite-austenite below the single-phase region of austenite is unfavorable due to the fact that in the process of hot rolling in the excited state is only the ferrite with the formation of large ferrite grains. Therefore, it is necessary to heat the slab to a temperature corresponding to the single-phase region of austenite (i.e tempera is URS, equal to or above the point AU3).

The temperature of the finish rolling: from 820°C to 930°C (including 820°C and excluding 930°C).

The temperature of the finish rolling equal to or greater than 930°C, leads to enlargement of part of the grains in the steel, thus leading to irregular and erratic distribution of ferrite grains in the steel. Accordingly, the temperature of the finish rolling in the present invention must be less than 930°C. thus the temperature of finish rolling shall be equal to or greater than 820°C. from the viewpoint of preventing the formation of large grains during hot rolling performed in the temperature region corresponding to the ferritic phase.

Steel sheet obtained in the above-mentioned hot rolling, is subjected to cooling and winding into a roll. The temperature of the winding in the winding process in a roll in the present invention is also important.

The temperature of the winding in a roll: from 540°C to 740°C (including 540°C and excluding 740°C).

The temperature of the winding into a roll equal to or greater than 740°C, escalates ferritic grain, in addition, slows down or becomes insufficient diffusion of carbon in the boundaries of ferrite grains during perezharivaya processing, resulting in formability obtained steel sheet is degraded. Accordingly, the temperature of the winding in the coil must be in the present invention below 740°C and suppose that the equipment be equal to 700°C or below. However, the temperature of the winding in a roll of less than 540°C suppresses the precipitation of nitrides in the hot-rolled steel sheet, causes the nitrides to stand out in a finely dispersed state in the annealing process after cold rolling, and thus, ultimately inhibits the growth of ferrite grains. Accordingly, the temperature of the winding roll is 540°C or higher.

The degree of compression during cold rolling: at least 55%.

The degree of compression when cold rolling is below 55% allow to remain in the initial state, the coarse cementite released at the boundaries of ferrite grains of the hot-rolled steel sheet, and this coarse cementite, apparently, is preserved in the resulting cold-rolled and annealed steel sheet inside the ferrite grains. Accordingly, the degree of compression during cold rolling must be at least 55%.

The heating temperature during annealing: 680°C or higher.

The heating temperature during annealing during continuous annealing, estimated at less than 680°C, leads to incomplete recrystallization. Accordingly, the heating temperature of the annealing should be 680°C. or higher. However, the heating temperature during annealing in excess of 900°C causes the formation of austenite and leads at the end of the process the grains of mixed sizes. Accordingly, the heating temperature during annealing is preferably sostav the em 900°C. or lower and more preferably 850°C. or lower.

The cooling rate from 680°C to temperature perestiani: at least 20°C/s

The cooling rate from the temperature after annealing to a temperature of perestiani should be under continuous annealing at least 20°C/s cooling Rate of less than 20°C/s reduces the driving force for the precipitation of cementite during perezharivaya processing, thus leading to insufficient precipitation of cementite and thereby impairing the formability of the obtained steel sheet. Accordingly, the cooling rate must be at least 20°C./sec and preferably at least 50°C/C. the Upper limit of the cooling rate, although it is a special way and is not limited to, an appropriate image can be set to about 350C°/s

Perezharivaya handling: 360°C or higher.

Temperature perestiani must be 360°C. or higher, since the temperature of perestiani less than 360°C promotes the precipitation of cementite within the ferrite grains. However, the temperature perestiani exceeding 550°C, rather prevents the precipitation of cementite. Accordingly, the temperature perestiani preferably set equal to 550°C or higher. In addition, perezharivaya processing is preferably performed for at least one minute, because too short a time perestiani does not provide enough what about the precipitation of cementite. Implemented in industrial conditions the upper limit time perestiani, although not too strongly influences the effect of the present invention, can be installed in about 10 minutes due to restrictions imposed on the production line.

As described above, the method of annealing can be performed either continuous annealing or annealing in containers. When annealing in containers, in which the steel sheet is gradually heated and gradually cooled, perezharivaya processing is not required. In addition, in the case of annealing in containers steel sheet slowly over a relatively long time is cooled from the heating temperature during annealing, resulting in carbon has sufficient time to diffuse into the boundaries of ferrite grains, and thus the formability of the resulting steel sheet is improved.

The temperature of annealing in containers: from 600°C to 750°C (including 600°C and 750°C).

In the case where annealing is carried out in containers, the annealing temperature in the containers must be in the range from 600°C to 750°C (including 600°C and 750°C), as the temperature of annealing in containers below 600°C allows you to remain in the initial state precrystallization areas of steel, and the temperature of annealing in containers of size 750°C leads to the formation of large grain is called

The time of annealing in containers although any particular way in the present invention is not limited, is preferably in the range from 1 hour to 40 hours, since the time of annealing in containers shorter than 1 hour are not able to provide a satisfactory exposure of the inner part of the roll, and the time of annealing in containers for more than 40 hours allows the carbon to Deposit on the surfaces of the obtained steel sheet and affects the quality of the surface of the steel sheet.

Training can be performed, or after perezharivaya processing during continuous annealing or after annealing in containers, although the presence/absence of training does not have a particularly strong impact on the effect of the present invention. The degree of compression when the training is preferably in the range from 0.5% to 1.5% (including 0.5% and 1.5%), because the degree of compression below 0.5% are not able to effectively deal with the elongation corresponding to the yield strength of the obtained steel sheet, and the degree of compression higher than 1.5% increases the hardness of the steel sheet.

Thus obtained cold-rolled steel sheet of the present invention may be subjected to processing for applying the coating for formation on the surface of the coating layer or a cladding film. Examples of coatings include zinc coating, education is Noah on the surface of the steel sheet, electrolytic method, and annealed zinc coating obtained by the exposure galvanized thus the steel sheet to annealing. Galvanizing and annealing can be performed on the same production line. Alternatively, the cladding film can be formed on the surface of the steel sheet, electrolytic plating, for example electrolytic coating of Nickel-zinc alloy, etc. In the case where cold-rolled steel sheet is subjected to processing, coating, training can be performed after the formation on the steel sheet as a result of such processing cladding coating.

Example 1

Samples of molten steel, having presented in the table 1 composition of the components were subjected to continuous casting to obtain slabs (steel materials), each of which had a thickness of 300 mm Each of thus obtained slab was heated to shown in table 2, the heating temperature of the slab corresponding to the single-phase region of austenite and subjected to finish rolling at a temperature of finish rolling is presented in table 2, and then subjected to winding into a roll at a temperature of winding into a roll, shown in table 2, the result of which was obtained hot rolled steel sheet having a certain thickness of the sheet. The sample obtained hot-rolled steel is th sheet was subjected to etching to remove from its surface descaling and cold rolling at the reduction degree, shown in table 2, to achieve a thickness of 1 mm thus Obtained sample cold-rolled steel sheet was subjected to in order to continuous annealing, cooling, and perezharivaya processing under appropriate conditions, shown in table 2. After perezharivaya processing this sample steel sheet was subjected to training when the degree of rolling of 1.0%. Each of the samples of the steel sheet, are presented in table 2 under No. 15-17, 24, was instead subjected to continuous annealing annealing in containers. For those subjected to annealing in containers of samples of sheet steel No. 15-17 and 24 perezharivaya treatment was omitted, and they were directly subjected to training when the degree of compression of 1.0%, respectively, as in the case of samples of leaves were subjected to continuous annealing.

In addition, each of the samples of cold-rolled steel sheet with the numbers in table 2 15-11 was subjected to electrolytic galvanizing way so that each of the front and back surfaces of the steel sheet formed of the obtained electrolytic galvanised cladding layer density of 30 g/m2(dry weight). Each of the samples of the steel sheet, are presented in table 2 under the numbers 22 and 23, was subjected to hot-dip dive so that each sparagna and back surfaces of such sheet formed of zinc cladding layer density of 45 g/m 2(dry weight). Samples of the steel sheet No. 22 and 23 were subjected to a tempering process after hot dip galvanizing, respectively.

Icons underscore under certain values in tables 1 and 2 indicate that these values are outside the scope of the present invention.

From each of the thus obtained samples of cold-rolled steel sheet samples were taken for testing, and using these samples for testing were performed tensile test.

In addition, it analyzed the formability of each of the thus obtained samples of cold-rolled steel sheet.

Methods of testing and measurement were as follows.

(i) the Study of structure.

Was determined the diameter of ferrite grains each thus obtained sample cold-rolled steel sheet by making the cross section of the steel sheet in the thickness direction of the sheet, cut parallel to the rolling direction, for a review of its structure; polishing the cross-section to a mirror finish; identifying patterns cross-sectional etching solution Natalia; photography obtained using an optical microscope image (×100) structure of the cross-section; drawing on the image grid of 10 lines in the direction of thickness, and is orthogonal to its direction, respectively, with intervals between adjacent lines of at least 100 μm (actual measurement); by counting the number of intersections between the boundaries of the ferritic grains and the data lines; dividing the total length of lines by the number of intersections to obtain the length of the line segment per one ferritic grain; by multiplying the length of a line segment in one of ferritic grain 1.13 and consideration of the thus obtained result of the computation as the diameter of ferrite grains according to ASTM (American society for testing and materials)".

(ii) analysis of the allocation of cementite.

Was defined as the proportion of cementite, segregated at the grain boundaries of each of the thus obtained sample cold-rolled steel sheet by making the cross section of the sample steel sheet in the thickness direction of the sheet, cut parallel to the rolling direction; polishing the cross-section to a mirror finish; identifying patterns of cross-section by etching with a solution of Petralia; photographing an image of the cross-structure under electron scanning microscope (×1000); consideration of localizations of cementite precipitation for the ten plots, respectively; determining the total area of allocation of cementite at the boundaries of ferrite grains and the total area of cementite in these ten areas; by dividing the total area of allocation of cementite at the boundaries of ferrite grains at deliciousa square cementite and consideration calculated so as a "fraction of cementite, segregated at grain boundaries".

(iii) the tensile Test.

From each of the thus obtained samples of cold-rolled steel sheet samples were taken JIS No. 5 tensile tests (JIS Z 2201), in which the direction of stretching the sample coincided with the direction parallel to the direction of rolling. Then were performed tensile test according to JIS Z 2241 using the sample to measure its tensile strength. Formability of each sample steel sheet was evaluated according to the measure of his uniform relative elongation. Uniform elongation is the elongation observed in the Annex to sample the maximum permissible load. Uniform elongation is used in the present invention as an indicator to assess formemost each sample steel sheet, because what is called "the formation of a neck", in which there is a local reduction in the thickness of the steel sheet are considered when punching mild steel sheet as a bad stamping, and so soft steel sheet during the test can be deformed only to the extent that only barely avoids local deformation or local manifestations of reducing the thickness of mild steel sheet.

From what ablity 2 shows, all samples of cold-rolled steel sheets according to the present invention show a uniform elongation of at least 20%, i.e. demonstrate excellent stampability.

Applicability in the production environment

According to the present invention it becomes possible to provide a cold-rolled steel sheet having a much better formability than conventional cold-rolled steel sheet, which is extremely useful from the point of view of industrial applications.

1. Cold-rolled steel sheet having high formability, contains, wt%:
With 0,010 to 0,035 (excluding 0,010)
Si 0.1 or less
Mn 0.35 or less
P 0,035 or less
S of 0.02 or less
N 0,0060 or less
Al 0.005 to 0.1
Fe and inevitable impurities rest
[%Mn]/[%Al]<20, where [% M] represents the content (wt.%) element M of steel, and the diameter of ferrite grains in the steel does not exceed 5 μm, and at least 50% of cementite is located on the borders of ferritic grains.

2. Steel sheet according to claim 1 which further includes In 0,0035 or less wt.%.

3. Steel sheet according to claim 1, which additionally contains at least one element selected from the group consisting of Cu, Sn, Ni, Ca, Mg, Co, As, Cr, Mo, Sb, W, Ti, Nb, Pb, TA, REM (rare earth the ways), V, Cs, Zr and Hf, so that their total content in the steel is 1 or less, wt.%.

4. Steel sheet according to claim 2 which further includes at least one element selected from the group consisting of Cu, Sn, Ni, Ca, Mg, Co, As, Cr, Mo, Sb, W, Ti, Nb, Pb, TA, REM (rare earth elements), V, Cs, Zr and Hf, so that their total content in the steel is 1 or less, wt.%.

5. Steel sheet according to any one of claims 1 to 4, which is made with the coating film on the surface of the sheet.

6. Method of manufacturing cold-rolled steel sheet having high formability, comprising preparing a steel material according to any one of claims 1 to 4, hot rolling a steel material including finishing rolling to obtain a steel sheet wound in a roll steel sheet after finish rolling, pickling, cold rolling, continuous annealing and perezharivaya processing with
steel material during hot rolling is heated to a temperature single-phase region of austenite and finish hot rolling at a temperature of finish rolling is in the range from 820°C to 930°C, including 820°C and excluding 930°C,
winding into a roll performed at a temperature in the range from 540°C to 740°C, including 540°C and excluding 740°C,
the etching is carried out with removing scale from the surfaces of the steel sheet,
cold rolling performed with a degree of compression at measures is 55%,
annealing is carried out at a heating temperature equal to or higher than 680°C,
annealed steel sheet is cooled from 680°C to temperature perestiani when the cooling rate is at least 20°C./s, and
perezharivaya treatment is carried out at a temperature equal to or greater than 360°C.

7. The method according to claim 6, in which are coated on the steel sheet after perezharivaya processing or annealing in containers.

8. Method of manufacturing cold-rolled steel sheet having high formability, comprising preparing a steel material according to any one of claims 1 to 4, hot rolling a steel material including finishing rolling to obtain a steel sheet wound in a roll steel sheet after finish rolling, pickling, cold rolling and annealing in containers, while
steel material during hot rolling is heated to a temperature single-phase region of austenite and finish hot rolling at a temperature of finish rolling is in the range from 820°C to 930°C, including 820°C and excluding 930°C,
winding into a roll performed at a temperature in the range from 540°C to 740°C, including 540°C and excluding 740°C,
the etching is carried out with removing scale from the surfaces of the steel sheet,
cold rolling performed with a degree of compression of at least 55%, and annealing in containers is carried out at a temperature in the range from 600°C to 70°C, including 600°C and 750°C.

9. The method according to claim 8, in which are coated on the steel sheet after perezharivaya processing or annealing in containers.



 

Same patents:

FIELD: chemistry.

SUBSTANCE: method involves preliminary deposition of rough layer with thickness of 0.01-3.0 mm on a metal surface using an electrical discharge method, followed by deposition of an antifriction layer. Electrical discharge deposition is carried out using electrodes made of medium- and high-carbon steels, and the antifriction layer is deposited with a paint gun with thickness of 0.5-1.5 mm using a composition consisting of mineral oil or a mixture of mineral oils based on saturated hydrocarbons, modified with nanoparticles of iron, formed during thermal decomposition of liquid iron pentacarbonyl, which is premixed in the medium of oil in a reactor with mixer rate of 1000-2500 rpm for 30-120 minutes, followed by feeding a ternary mixture of powdered filler into said reactor while mixing, said mixture consisting of graphite (A), molybdenum disulphide (B) and tetrafluoroethylene polymer (C) in ratio A:B:C from 40:40:20 to 80:10:10. Said composition contains the following, pts.wt: mineral oil or mixture of mineral oils 100, iron nanoparticles 0.3-4.0 and ternary mixture of powdered filler 15-60.

EFFECT: prolonged antifriction action of the deposited coating.

2 tbl, 5 ex

FIELD: metallurgy.

SUBSTANCE: hot formed element of coated sheet steel surface layer comprises are of Ni diffusion, intermetallide compound layer and ZnO layer. Said layers are overcoated with Ni diffusion area. Intermetallide compound layer corresponds to γ-phase displayed at Zn-Ni alloy phase equilibrium diagram. Said layer has intrinsic potential of submersion in air-saturated water solution of NaCl with 0.5 mol/l concentration at 25 °C±5°C in the range of -600 to -360 mV relative to standard hydrogen electrode. Said element is produced by heating sheet steel with Ni-based coat containing on its surface a layer of coat from Zi-Ni alloy containing 13 wt % of mote of Ni in the temperature range of Ac3 transition to 1200°C with subsequent hot forming of steel sheet.

EFFECT: higher corrosion resistance, better coat adhesion.

16 cl, 3 dwg, 4 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: timber surface is coated with a ply of liquid glass prior to deposition. Ply of aluminium powder is powdered on non-solidified surface of aforesaid ply. Deposition of metal or alloy plies is effected by plasmatron at the power of 4.5 kW and plasma-forming gas flow rate of 0.5 m3/min.

EFFECT: higher quality, longer life, lower labor and power input.

2 ex, 3 tbl

FIELD: metallurgy.

SUBSTANCE: beforehand, wood surface is coated with first ply of epoxy resin and second ply of epoxy resin with aluminium powder at 1:1 ratio. Deposition of metal or alloy plies is effected by plasmatron at the power of 3.9 kW and plasma-forming gas flow rate of 0.8 m3/min.

EFFECT: higher quality, longer life, lower labor and power input.

2 ex, 3 tbl

FIELD: metallurgy.

SUBSTANCE: plate is made from steel containing the following, 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 or less and Pe and impurities are the rest provided that [% Mn]/[% C]≥2.0, where [% M] represents content (wt %) of M element in steel, which has tensile strength (TS) at least of 390 MPa, relative elongation (EE) at least of 30% and elongation corresponding to yield point, (YP-EL) after ageing with constant increase in steel plate temperature, which does not exceed 1.0%.

EFFECT: increased ductility of steel plate.

12 cl, 3 dwg, 3 tbl

FIELD: metallurgy.

SUBSTANCE: part includes a substrate, a lustre nickel coating layer above the substrate, a nickel coating layer with precious potential on the lustre nickel coating layer; with that, difference of electrical potentials between the above layers is within 40 mV to 150 mV, and a trivalent chrome coating layer formed on the nickel coating layer with precious potential and having at least one of the structure with micropores and structure with microcracks. Trivalent chrome coating layer has 10000/cm2 or smaller pores or includes 4.0 to 20 atm % of carbon and 7 to 16 atm % of oxygen, or has been obtained by means of the main chromic sulphate as metal source and in addition it contains 0.5 atm % of iron or more, or contains at least one of 0.5 atm % of iron or more and 4.0 atm % of carbon or more, or contains at least one of 1 atm % to 20 atm % of iron and 10 atm % to 20 atm % of carbon, or is amorphous. The method involves formation of the lustre nickel coating layer above the substrate, formation of layer of nickel coating with precious potential on the lustre nickel coating layer; with that, difference of electric potentials between layers is 40 to 150 mV, and electric deposition of the trivalent chrome coating layer on the layer of nickel coating with precious potential. Amount of electric potential regulator added to the first electrolytic bath for formation of the layer of nickel coating with precious potential is regulated so that it can be higher than the amount added to the second electrolytic bath for formation of a lustre nickel coating layer.

EFFECT: improvement of part characteristics.

10 cl, 7 dwg

FIELD: electricity.

SUBSTANCE: heteroepitaxial semiconductor film on a single-crystal silicon substrate is grown by the method of chemical deposition from the gas phase. Synthesis of the heterostructure SiC/Si is carried out on a single-crystal silicon substrate in a horizontal reactor with hot walls by means of formation of a transition layer between the substrate and the film of the silicon carbide with the speed of not more than 100 nm/hour with heating of the specified substrate to the temperature from 700 to 1050°C with application of a gas mixture containing 95-99% of hydrogen and the following sources of silicon and carbon SiH4, C2H6, C3H8, (CH3)3SiCl, (CH3)2SiCl2, at the same time C/Si≥2, and formation of the single-crystal film of silicon carbide with the help of supplu of steam and gas mixture of hydrogen and CH3SiCl3 into the reactor while maintaining absolute pressure in the reactor in the range from 50 to 100 mm of mercury column. The silicon substrate is a plate that has an angle of inclination of crystallographic direction (111) in direction (110) from 1 to 30 of angular degrees and in direction (101) from 1 to 30 angular degrees.

EFFECT: improved compatibility of two materials of a silicon carbide layer and a silicon substrate with different period of crystalline lattices, at the same time mechanical stresses in a heterostructure are reduced, and lower densities of defects in a layer of silicon carbide are achieved.

6 cl, 3 dwg, 3 ex

FIELD: metallurgy.

SUBSTANCE: proposed method involves pre-cleaning of the steel product surface to be coated; application onto cleaned surface of the product of a flux layer by means of a gas-powder surfacing method with warm-up of the processed part of the product of up to the temperature of 450-600°C at use of propane-butane gas mixture; submersion of the product into molten wearproof steel at the melt temperature of 1560-1650°C; exposure in the melt during the period of time, which is required to obtain a coating of the required thickness; removal of the product with the coating out of the melt with further slow cooldown of the product with the applied coating in the air or together with a tight furnace with initial temperature of 500-600°C.

EFFECT: invention allows obtaining wearproof coatings with thickness of several millimetres applying a simple and economic method.

2 cl

FIELD: metallurgy.

SUBSTANCE: proposed method comprises formation of porous anodic oxide layer by anode oxidation of titanium specimen at controlled potential electrolysis in nonaqueous electrolyte solution. Note here that after said formation, anodic oxide is separated by electrochemical process in weak aqueous solution of inorganic acid by cathodic polarisation of titanium specimen controlled potential electrolysis. Then, secondary layer of porous anodic titanium oxide is formed under the above described conditions. Note that anodic oxidation of titanium specimen for formation of both said layers is conducted at thermal stabilisation of electrochemical reaction.

EFFECT: better reproducibility of the process and high degree of nanostructure order.

3 cl, 2 dwg, 1 ex

FIELD: machine building.

SUBSTANCE: protected surface of parts is prepared, a sublayer is applied, and chemical-thermal treatment of parts is carried out. The sublayer is applied from silicon or powdery metals from a group of transition metals, or metals of chrome subgroup with the help of plasma sputtering. Chemical-thermal treatment of the sublayer is carried out in a powder-type layer containing an active powder mixture at the following ratio of reagents, wt %: ammonium chloride not more than 5, titanium or aluminium or nickel 39-50, aluminium oxide and/or titanium diboride 4-55, carbon or boron, or silicon, or silicon carbide - balance. Saturation of the sublayer with the active powder mixture is carried out under vacuum or in a protective medium from inert gas under thermal treatment for 1-4 hours at the temperature in the range of 800-1100°C.

EFFECT: improved quality of a coating due to its increased thermal resistance, chemical resistance and mechanical strength.

2 dwg, 2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, and namely to production of a high-strength hot-rolled steel plate with excellent fatigue strength. Steel contains the following, wt %: C: 0.08-0.18, Si: less than 0.5, Mn: 0.8-1.8, P: 0.05 or less; S: 0.005 or less; N: 0.008 or less; Al: 0.01-0.1, Ti: 0.01-0.1, Fe and inevitable impurities are the rest, heated to the temperature of 1150-1300°C. Hot steel rolling is performed with rolling end temperature in the range of Ar3 to (Ar3+60)°C and with a crimping degree in the last frame of finishing rolling of not less than 25% to obtain a steel plate. The plate is coiled at the temperature of 570-670°C. Microstructure of some part of a surface layer to the depth from surface of up to 100 mcm consists of ferrite as the primary phase and the secondary phase, the fraction of which is 30% or less. Average diameter of ferrite grain is maximum 10 mcm. At least 30% of Ti contained in some part of the surface layer is present in the form of Ti carbide, and average diameter of Ti carbide grain does not exceed 30 nm.

EFFECT: produced steel plates have high fatigue strength and formability.

9 cl, 1 dwg, 3 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: steel sheet parent metal comprises the following components, in wt %: 0.010-0.080%, Si: 0.01-0.50%, Mn: 0.50-2.00%, S: 0.0001-0.0050%, Ti: 0.003-0.030%, Mo: 0.05-1.00%, B: 0.0003-0.0100%, O: 0.0001-0.0080%, N: 0.006-0.,0118%, P: at least 0,050% or smaller, Al: at least 0.008% or smaller, Fe and unavoidable impurities making the rest. Carbon equivalent (Ceq) makes 0.30 to 0.53, crack growth resistance in welding (Pcm) makes 0.10 to 0.20, while [N]-[Ti]/3.4 does not exceed 0.003. Mean size of primary γ-grains in thermal effects zone in steel sheet makes 250 mcm or smaller, while primary γ-grains include bainite and intragranular bainite.

EFFECT: sufficient low-temperature toughness.

9 cl, 3 dwg, 2 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: plate is made from steel containing the following, 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 or less and Pe and impurities are the rest provided that [% Mn]/[% C]≥2.0, where [% M] represents content (wt %) of M element in steel, which has tensile strength (TS) at least of 390 MPa, relative elongation (EE) at least of 30% and elongation corresponding to yield point, (YP-EL) after ageing with constant increase in steel plate temperature, which does not exceed 1.0%.

EFFECT: increased ductility of steel plate.

12 cl, 3 dwg, 3 tbl

FIELD: metallurgy.

SUBSTANCE: steel contains the following, wt %: C 0.06 to 0.12, Si 0.01 to 1.0, Mn 1.2 to 3.0, P 0.015 and less, S 0.005 and less, Al 0.08 and less, Nb 0.005 to 0.07, Ti 0.005 to 0.025, N 0.010 and less, O 0.005 and less, Fe and inevitable impurities are the rest. Steel microstructure represents a two-phase microstructure consisting of bainite and martensite-austenite component (M-A); fraction of surface area of M-A component is in the range of 3% to 20%, and equivalent diameter of a circle for M-A component is 3.0 mcm and less.

EFFECT: steel is characterised by uniform relative elongation and ratio between yield point and ultimate strength both before and after strain ageing during 30 minutes and less.

3 cl, 3 dwg, 3 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: non-textured plate from electrical steel contains the following, wt %: Si not less than 1.0 and not more than 3.5, Al not less than 0.1 and not more than 3.0, Ti not less than 0.001 and not more than 0.01, Bi not less than 0.001 and not more than 0.01, C 0.01 or less, P 0.1 or less, S 0.005 or less, N 0.005 or less, Fe and impurities are the rest. With that, the following ratio is executed: [Ti]≤0.8×[Bi]+0.002.

EFFECT: magnetic properties are improved.

22 cl, 4 dwg, 5 tbl, 36 ex

FIELD: metallurgy.

SUBSTANCE: plate is made from steel containing the following components, wt %: C 0.005 ore less, Si 10 to 8.0, Mn 0.005 to 1.0; one or more elements chosen from Nb, Ta, V and Zr; with that, their total content is 10 to 50 ppm, and Fe and inevitable impurities are the rest. At least 10% of Nb, Ta, V and Zr content is in the form of particles of the separated phase, the particles of which have average diameter, - diameter of equivalent circle - 0.02 to 3 mcm, and grains of a steel plate, which are recrystallised for the second time, have average size of 5 mm or higher.

EFFECT: reduction of deterioration of magnetic characteristics in case a plate is subject to shear as a result of the cutting process, even without performance of an annealing operation for release of stresses.

4 cl, 2 dwg, 3 tbl, 3 ex

FIELD: metallurgy.

SUBSTANCE: plate steel contains the following, wt %: 0.03% to 0.06% C, 0.01 to 1.0 Si, 1.2 to 3.0 Mn, 0.015 and less P, 0.005 and less S, 0.08 and less Al, 0.005 to 0.07 Nb, 0.005 to 0.025 Ti, 0.010 and less N, 0.005% and less O, and Fe and inevitable impurities are the rest; steel has three-phase microstructure consisting of bainite, martensitic-austenitic component (M-A) and quasi-polygonal ferrite; with that, bainite surface area is equal to 5% to 70%; M-A component surface area is 3% to 20%; and quasi-polygonal ferrite occupies the rest surface area, and equivalent diameter of a circle for M-A component is 3.0 mcm and less. Plate steel is characterised by the ratio between yield point and limit strength, which is equal to 85% and less, and absorbed energy during the Charpy impact test at the temperature of -30°C, which is equal to 200 J and more, before and after treatment in the form of strain ageing at the temperature equal to 250°C and less, during 30 minutes and less.

EFFECT: provision in plate steel of low ratio between yield point and limit strength, high strength, impact strength and stability to strain ageing, which is equivalent to Class API 5L X60 and less.

4 cl, 3 dwg, 3 tbl, 1 ex

FIELD: metallurgy.

SUBSTANCE: steel which contains the following, wt %, is heated: 0.02-0.08 of C, 0.01-0.50 of Si, 0.5-1.8 of Mn, 0.025 or less of P, 0.005 or less of S, 0.005-0.10 of Al, 0.01-0.10 of Nb, 0.001-0.05 of Ti, the rest is Fe and inevitable impurities, at that content of C, Ti and Nb complies with the ratio (Ti + (Nb / 2)) / C <4. Hot-roll is performed including roughing-down and finish rolling, accelerated cooling at average rate of cooling in the middle of steel plate in the thickness direction equal to 10°C/s or more till temperature of cooling stop is reached, and it is coiled under coiling temperature. Steel microstructure includes ferritic phase being the primary phase and including bainitic ferrite, bainit and their mixed phase and the second phase including pearlite, martensite, austenitic-martensitic component and their mixed phase. Difference ΔD between average size of grain (mcm) of ferritic phase at a distance of 1 mm from the surface of steel plate in the direction of thickness and average size of grain (mcm) of ferritic phase in the middle of steel plate at a distance of 2 mcm or less in the direction of thickness, and difference ΔV between content part (vol %) of the second phase at a distance of 1 mm from the surface of steel plate in the direction of thickness and content part (vol %) of the second phase in the middle of steel plate in the direction of thickness is 2% or less.

EFFECT: providing steel with characteristics of high tensile strength TS in 521 MPa and improved low-temperature impact strength, improved values of DWTT and CTOD.

14 cl, 7 dwg, 12 tbl

FIELD: metallurgy.

SUBSTANCE: rail from high-carbon pearlite steel, which has increased ductility, which contains the following components, wt %, is proposed: C: more than 0.85 to 1.40%, Si: 0.10%-2.00%, Mn: 0.10%-2.00%, Ti: 0.001%-0.01%, V: 0.005%-0.20%, N: less than 0.0040%, Fe and inevitable impurities are the rest. Contents of Ti and V meet the following formula: 5≤[V(wt %)]/[Ti(wt %)]≤20. Head part of the rail has pearlite structure. Method for obtaining pearlite rail involves hot rolling of bloom, finishing rolling of the hot rolling stage under conditions when temperature of finishing rolling FT, °C is established in the following range: Tc-25≤FT≤Tc+25. Tc=850+35×[C]+1,35×104x[Ti]+180×[V].

EFFECT: rails have increased ductility and wear resistance.

3 cl, 10 dwg, 5 tbl, 15 ex

FIELD: metallurgy.

SUBSTANCE: proposed composition contains the following substances, in wt %: carbon 0.27 - 0.32, titanium 5.8 - 6.2, nickel 0.5 - 0.9, titanium carbide (TiC) 0.5 -1.5, iron making the rest. Besides, it may contain up to 0.05% traces of manganese, 0.15 - 0.17% of silicon, and ≈0.03% of sulfur and phosphorus. Titanium carbide is added in the form of powder with particle size of up to 10 mcm into ladle or in melt jet in teeming steel into metallic chill mould.

EFFECT: improved processing and operating properties, lower costs.

2 tbl

FIELD: metallurgy.

SUBSTANCE: steel containing Si is subjected to cold rolling, decarburizing annealing for primary recrystallisation, sheet coiling and coil group annealing for secondary recrystallisation. Steel sheet coil is unwound and straightened. Right between cold rolling and coiling, silicon sheet steel is irradiated by laser beam multiple times in definite intervals from one end to another over sheet width. At secondary recrystallisation, boundaries of grains extending from front surface to rear surface along laser beam paths.

EFFECT: higher density of magnetic flux, lower magnetic loses.

11 cl, 18 dwg, 3 tbl, 2 ex

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