Cold resistant steel

FIELD: metallurgy, namely cold resistant steels.

SUBSTANCE: cold resistant steel for machines and apparatuses, namely in gas- and oil production industry operating in condition of cold climate. Such steel contains, mass %: carbon, 0.15 - 0.22; manganese, 0.3 - 0.6; silicon, 0.15 - 0.40; vanadium, 0.08 -0.12; titanium, 0.001 - 0.040; niobium, 0.001 - 0.040; aluminum, 0.03 - 0.06; sulfur, 0.010 - 0.020; phosphorus, 0.010 - 0.020; cerium, 0.005 - 0.05; calcium, 0.001 - 0.01; barium, 0.001 - 0.01; iron, the balance.

EFFECT: improved strength and cold resistance of steel.

5 tbl

 

The invention relates to metallurgy, in particular to the development of steels for machinery and apparatuses, in particular oil and gas industry, operating in conditions of cold climate with a high level of cold resistance and mechanical properties, high operational reliability of the equipment during its long-term operation at low temperatures.

One of the main materials used in the manufacture of equipment for oil and gas are high-quality carbon steel, such as steel 10 and 20, manufactured according to GOST 1050-88. However, the minimum allowable operating temperature of the equipment made from these steels limited by Rules on construction and safe operation of equipment GGTN RF temperature of minus 40°With, while in the Northern regions of the Russian Federation, the temperature in winter can drop below minus 60°C. Another feature of the exploitation of oil and gas production and processing industry is increasing the capacity of the equipment and, as a consequence, a significant increase in requirements for strength properties of the materials used. However, increasing the strength of the steel leads to a reduction of reserves its viscosity, plasticity, tremino - and cold-resistance. Casticin is this problem solved by the replacement of less expensive carbon steel more expensive alloy brand, however, such a replacement leads to a significant increase in the cost of newly manufactured equipment, reducing its competitiveness. This requires exploration of alternative ways to increase strength and cold resistance already used materials.

So by increasing the strength and brittle fracture of steels is the regulation of grain size in steels that can be achieved by changing the mode of its heat treatment, for example, by changing the final heat treatment with normalization of carbon steels in the regime of thermal Cycling, the introduction of steel microeconomic additives restraining the grain growth of steel during high-temperature treatments.

Mechanical properties of carbon steels, including yield strength, are directly dependent on their structural condition, including the size and composition of individual grains, the presence of disperse excess phases - their shape, size, location. To calculate the value of the yield strength of steel as a polycrystalline body consisting of a homogeneous grains of solid solution, it is possible, using the equation of the Petch-Hall:

σof 0.2i+Kyd-1/2

where σi- tension friction - the resistance to movement of dislocations in the lattice of the solid solution. It is caused by the resistance of the lattice h is stage iron (Peierls force, including), and hardening introduced by dislocations, the dissolved atoms of impurities and alloying elements, the discharge of dispersed phases. Kyd-1/2reflects the proportion of hardening and grain boundaries, d is the average grain size, Ky- correlation coefficient.

In the same way it is possible to calculate the effect size of the actual grain steel on her gladstonos. According to theory of Cottrell-Petch when the hardening matrix BCC alloys is their susceptibility to brittle fracture should increase in accordance with the criterion of change:

id-1/2+Ky)Ky=Gβγ.

Substituting the expression (2) into the equation of the Petch-Hall, get:

σof 0.2Kyd-1/2=Gβγ,

where G is the modulus of elasticity in shear, β - coefficient taking into account the stress-strain state and γ is the effective surface energy of destruction. As follows from the obtained expression the only factor preventing embrittlement is grinding grain steel. Using the results of modern studies of solid state physics, it is possible to obtain an expression that allows one to calculate the change in temperature of the viscous-brittle transition in steel, depending on the size of the actual grain:

TXP=M+Nln d-1/2,

where M and N corresponding CoE who ficiency.

The positive influence of the decrease of grain size on the temperature of the ductile-brittle transition can be attributed to a more uniform distribution of impurity elements within the boundaries of crushed grains, smaller quantities of grain boundary segregation of impurity atoms, and, first and foremost, the smaller value of grain boundary segregation of phosphorus atoms, element, exerting a decisive influence on the ductile-brittle transition temperature.

However, despite the existing theoretical justification for the selection of steels, their heat treatment and ways to improve the reliability and durability of these materials, until now, has not formed a unified concept for optimizing the selection of steels for equipment operated in the Northern regions of the country. Also there are no evidence-based recommendations on the technology of smelting, steel deoxidation for the Northern regions of the country and assignment conditions of thermal treatment.

To reduce the grain size of steels may the best technology of smelting, microregionalism, the use of rare-earth and alkaline-earth metals to globularization non-metallic inclusions. Plays an important role in the optimization of heat treatment.

Based on the need to ensure high-strength steels, while maintaining high the level of resistance to brittle fracture and brittle fracture is the most promising for the development of the optimal composition is the group of carbon steels, which were introduced microeconomie additives of one or more elements from the group of vanadium, zirconium, niobium and titanium. The analysis of the influence of alloying of steel these elements and the role of additives REM and SSM. Given that the main requirements of steels used in the climatic conditions of cold, is the increased strength while maintaining maximum low temperature ductile-brittle transition these parameters were chosen in the optimization of the composition of the steel.

Famous steel, similar in composition to declare - steel for welded structures with the viscosity of the heat-affected zone is not dependent on energy welding, and a method of manufacturing steel.

Application 1143023 EPO IPC7With 22 38/00, With 21 7/00 Nipon Steel Corp., Uemori Ryuji, Tomita Yukio, Hara Takaja, Shuji Aihara, Naoki Saitoh. No. 00966448.3. Appl. 12.10.2000, publ. 10.10.2001, prior. 12.10.1999, No. 28941299 (Japan). Eng.

Structural steel: U.S. Pat. 30639 Ukraine, IPC6With 22 38/44. Kurdyukov A.A., Bobilov M.V., Noshchenko O.V., Miller SG, bug I.D., Canag M.I., Tagirov IV, Kukush SF No. 98031619, Appl. 31.03.1998; Publ. 15.12.2000. RBM. Steel: U.S. Pat. 2217520 Russia, IPC7With 22 38/54 Fedchenko Y.A., Burial grounds O.V., Robozerov NV, Sulacco VI, Shahmen SR, Dudarenko B.C. No. 2002103562/02; Appl. 08.02.2002; Publ. 27.11.2003. Eng.

Structural steel: U.S. Pat. 60653 Ukraine, IPC721 With 5/00, Rabinovich O.V., Tregubenko G.M., Tarasyev M.I. Ignatov MV, Pachikov O.V., Zaslavsky SHE Bagels CREATING no 2003010641; Appl. 24.01.2003; Publ. 15.10.2003. Ukr.

Steel for welded structures Sato SEI, Haji Toshiaki, Kana Ken. Application 57-207156, Japan, Appl. 12.06.81, No. 56-90444, publ. 18.12.82. MKI With 22 38/14, With 22 38/54.

The steel. Nasibov A.G., Sailors SCI, Litvinenko D.A., Golovenko S.A., Ed. VSS, CL 22 With 38/16, No. 755881, Appl. 16.02.78, No. 2582838, publ. 15.08.80.

Steel Pat. No. 2025532, Russia, MKI5With 22 38/14. Smirnov, L., Panfilov L.M., Rogovich M.I., Sokolova GI No. 5042113/02; Appl. 15.02.92; Publ. 30.12.94. Bull. No. 24.

Surface-hardened alloy steel and products made from it. Pat. U.S. CL 75/124 (With 22 38/42, With 22 38/44), No. 4157258, Appl. 18.08.78, No. 935003, publ. 5.06.79

From the known steels, the most similar to the claimed composition, and is selected as a prototype, is steel Steel: U.S. Pat. 2179196 Russia, IPC7With 22 38/14. JSC "Severstal", Dyakonov B.C., Latysheva THUS, Zinchenko S.D., Menshikov GA, Medvedev, A.P., Tetyeva T.V., Prokhorov, N.N., Osipov M., Us O.S. No. 99127777/02; Appl. 28.12.1999; Publ. 10.02.2002, having the following composition wt.%

carbon 0.05 to 0.15; si 0,30-0,90; manganese - 0,40-0,90; sulfur - 0,001-0,020; phosphorus - 0,005-0,020; titanium - 0,001-0,040; vanadium - 0,05-0,20; aluminum - 0,01-0,08; niobium - 0.01 to 0.08.

Studies have shown that steel prototype does not have sufficient mechanical properties and wear resistance.

Technical achiev what tatom of this work is to increase the strength and brittle fracture of steel.

When establishing the proper ratio of the components originated from the following assumptions.

Lowering the carbon content below 0.15% does not provide requirements on strength characteristics of the steel, the increase of the carbon content of more than 0,22% deteriorates the weldability, complicates the machinability of steel.

The silicon content is less than 0.15% does not provide a satisfactory deoxidation of steel, which can contribute to formation porosity. Increasing the concentration of silicon than 0.4 percent increases the probability of formation of grain boundary segregation of this element, and, consequently, leads to embrittlement of the steel at low temperatures.

Manganese contributes to the grinding of the grains in the steel increases the strength of the solid solution, provides the deoxidation. Manganese concentration less than 0.3% does not meet the requirements for deoxidation of steel, which results in the grain boundaries of steel segregation of sulfur, and an increase of more than 0.6% increases the propensity for the formation of cold cracks during welding, the temperature increase of the ductile-brittle transition.

Sulfur and phosphorus are the most dangerous from the point of view of the development of fragile defects, impurities in carbon and alloy steels. Their content more 0,020% each contributes to the intensification of the development of grain boundary segregation, reducing the cohesion of grain boundaries,less than 0,010% sulfur and 0.010% phosphorus - technically extremely difficult and greatly increases the cost of the material.

Alloying with vanadium, niobium and titanium in the limits of its solubility in the ferrite leads to a sharp grinding grain steel to improve its strength properties, increases crack resistance, reduces the likelihood of zerogravity segregation of impurity atoms, prevents grain growth during process heating and heat treatment.

The introduction of the steel, aluminum, MSM and REE are associated with their high rascalities refining and modifying ability. Reducing gas, sulfur, globulariaceae non-metallic inclusions provide a high level of fracture toughness, protecting the steel from brittle fracture. Spheroidizing of non-metallic inclusions accompanied by cleansing crystal boundaries and a uniform distribution of inclusions in the metal.

The claimed steel contains components in the following ratio, wt.%

Carbon 0,15-0,22

Manganese 0,3-0,6

Silicon 0,15-0,40

Vanadium 0,08-0,12

Titanium 0,001-0,040

Niobium 0,001-0,040

Aluminum 0,03-0,06

Sulfur 0,010-0,020

Phosphorus 0,010-0,020

Cerium 0,005-0,05

Calcium 0,001-0,01

Barium 0,001-0,01

Iron - rest.

Studies have been conducted of the actual size of the grains mechanical properties and cold resistance became the prototype and the claimed steel. To test the s mechanical properties were fabricated samples for testing static stretching according to GOST 1497. The impact toughness and gladstonos (transitional ductile-brittle transition temperature) was performed on samples of type 11 according to GOST 9454 estimate of the actual grains was carried out in accordance with GOST 5639, the analysis of the chemical composition of the grain boundaries and the determination of the magnitude of grain boundary segregation were conducted by the method - ECO (Auger electron spectroscopy). The sensitivity of the method is 10-1-10-2%accuracy analysis of 5-10% with depth resolution within 3-30 Å. Studies were performed on ESCA/AES spectrometer PHJ-548. K.

Experienced steel has high strength, ductility and toughness. Found grinding grain steel and level of grain boundary segregation of impurity elements, primarily phosphorus in the grain boundaries of the steel. Research impact strength at low temperatures showed a significant reduction in the ductile-brittle transition temperature.

Thus, the claimed steel can be used for the manufacture of units and parts of machines, mechanisms and units operating in low temperature conditions climatic cold coldest regions of the country, in Siberia, the Far North and Sakhalin.

Steel prototype and melting of the inventive steels with different compositions on the upper and lower levels of alloying elements were produced in the open is the first high-frequency induction furnace with a capacity of 100 kg with a basic lining submerged composition 92% CaF 2at 3.5% Cao, 2% SiO2, 1.8% of Al2O3and the number distributed.

Were made of the samples of the inventive steel of the four compounds (table 1).

The melt temperature of the bottoms of the claimed steel and steel-prototype before production was within 1500-1550°C. the composition of the experimental heats conducted conventional chemical method and analysis of the material on the quantometer Philips. The verification of the results produced by vacuum melting in JSC "Izhora plants".

Table 1

"Chemical compositions of the experimental heats of the claimed steel and steel prototype".
The composition of steelMnSiVTiNbAlSPCECAVAFe
The placeholder0,150,600,400,200,0400,0800,0200,0180,018---Rest
10,150,300,150,080,0010,0010,0300,0100,0100,05 0,0010,001
20,180,450,270,100,0200,0200,0450,0150,0150,0300,0060,006
30,220,600,400,120,0400,040to 0.0600,0200,0200,0500,0100,010
40,220,600,400,100,030,03to 0.0600,0100,0100,0500,0100,010

Each of the experimental melts were poured into four ingot weighing 25 kg each. Before pressure treatment, the ingot was subjected to Stripping, and their profitable and bottom parts were removed. Forging was performed on the hammer with a force of 1 ton

The temperature interval of forging was 1200-1170°C. Heating is produced at a rate not exceeding 50 per hour to a temperature of 1250-1280 K. At this temperature, was given a two-hour exposure. Further, without limiting the speed of the temperature was raised to 1470±10 To and withstand the ingots at this temperature for 2 hours, the Heating was controlled by chromelalumel thermocouple. Filing under the hammer Molo is not exceeded 80-100 mm at a time. By lowering the temperature of the workpiece to 1180±10 For it was placed in an oven with a temperature of 1470 K and kept it in 1 hour.

Before heat treatment of forgings cut on the workpiece under the samples for the required types of tests. For sample preparation, we used the workpiece 14×14×500 mm Obtained billet samples were subjected to thermal processing.

Heating of the billets produced in a laboratory furnaces of the type "SNA". The results of testing the mechanical properties of the inventive steel of the prototype are given in table 2.

In table 3 shows the values of the transition temperature of the ductile-brittle transition, determined by the ratio of viscous and brittle component on the surface of the fracture - (T50).

Table 2

"Mechanical properties of experimental heats of the claimed steel and steel-prototype"
Mechanical propertiesσof 0.2, MPaσB, MPaδ, %ψ, %KCV, MJ/m2K1CMPa m1/2
The placeholder30548533681,1258
133550036671,22 70
234651534681,3070
334152537701,1474
435253736671,1071

Table 3

"Transitional ductile-brittle transition temperature experienced the bottoms of the claimed steel and steel-prototype"
fusionthe placeholderHeat 1Heat 2Heat 3Fusion 4
Transitional ductile-brittle transition temperature (T50)-44-57-64-61-63

The enhancement of the mechanical properties and increase the cold resistance of the inventive steel against the steel properties of the prototype should be associated with the grinding of the grain of the steel due to the optimum microalloying (table 4). Also the improvement of these characteristics should be associated with a decrease in the total concentration of impurity elements in the grain boundaries of steel (grain boundary segregation), as well as a significant decrease in the content within the boundaries of the most dangerous from the point C the value of brittle fracture of steel impurities - phosphorus (table 5)

Table 4

"The average grain size in the experimental trunks of the claimed steel and steel-prototype"
fusionthe placeholderHeat 1Heat 2Heat 3Fusion 4
The average size (diameter) grain steel (μm)59-6631-4237-4139-4338-42
Table 5

"Total concentration of the impurity atoms and phosphorus atoms in the grain boundaries experienced the bottoms of the claimed steel and steel-prototype"
fusionthe placeholderHeat 1Heat 2Heat 3Fusion 4
The total amount of grain boundary segregation of impurity elements (atomic %)*18,311,2the 10.110,510,2
The amount of grain boundary segregation of phosphorus atoms (atomic %)*6,44,33,7a 3.93,7
* the thickness of the analyzed layer 10 angstroms.

Thus, the developed brand cold-resistant steel, designed for machines and devices, the particular oil and gas industry, operating in conditions of cold climate with a high level of cold resistance and mechanical properties and high operational reliability of the equipment during its long-term operation at low temperatures.

Cold-resistant steel for machines and devices, in particular oil and gas industry, operating in conditions of cold climate, containing carbon, manganese, silicon, vanadium, titanium, niobium, aluminum, sulfur, phosphorus and iron, characterized in that it further comprises cerium, calcium and barium in the following ratio, wt.%:

Carbon0,15-0,22
Manganese0,3-0,6
Silicon0,15-0,40
Vanadium0,08-0,12
Titanium0,001-0,040
Niobium0,001-0,040
Aluminum0,03-0,06
Sulfur0,010-0,020
Phosphorus0,010-0,020
Cerium0,005-0,05
Calcium0,001-0,01
Barium0,001-0,01
IronRest



 

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FIELD: ferrous metallurgy; motor-car industry; production of steels intended for manufacture of items of a complex configuration with the help of cold sheet stamping.

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EFFECT: the invention allows to boost the steel stamping, to improve the quality of the steel strip surface and adhesion of a protective cover.

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Structural steel // 2251587

FIELD: metallurgy, in particular structural steel composition.

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EFFECT: steel with optimum combination of strength and viscous properties.

2 tbl, 1 ex

FIELD: metallurgy; production of important rolled stock for oil-well tubing of increased service life.

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FIELD: metallurgy; high-titanium-bearing foundry alloy production.

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FIELD: ferrous metallurgy.

SUBSTANCE: invention provides round-profiled iron smelted from low-carbon steel composed of, wt %: carbon 0.17-0.25, manganese 0.30-0.65, silicon 0.01-0.17, sulfur 0.005-0.020, vanadium 0.005-0.07, niobium 0.005-0.02, calcium 0.001-0.010, iron and unavoidable impurities - the balance. When following relationships are fulfilled: 12/C-Mn/0.02 ≥ 27; 0.46 ≥ 6V+8Nb ≥ 0.22; Ca/S ≥ 0.065, rolled iron has following characteristics: maximum degree of pollution with nonmetal inclusions, in particular sulfides, oxides, silicates, and nitrides, does not exceed 3 points for each type of inclusions; longitudinally uniform spheroidized structure composed of at least 80% grainy perlite; effective grain size 5-10 points; diameter 10-25 mm; carbon-free layer not exceeding 1.5% of diameter; cold setting value at least 1/3 height; point of maximum load not higher than 550 MPa; relative elongation at least 20%; and relative contraction at least 60%.

EFFECT: ensured optimal conditions for cold die forging of high-strength geometrically complex fastening members and simultaneously ensured improved characteristics of in-process plasticity and low level of stray hardening.

FIELD: ferrous metallurgy.

SUBSTANCE: invention provides round-profiled iron smelted from alloyed steel composed of, wt %: carbon 0.06-0.11, manganese 0.30-0.9, silicon 0.001-0.15, boron 0.0005-0.0050, vanadium 0.005-0.08, aluminum 0.02-0.06, titanium 0.01-0.04, sulfur 0.005-0.020, nitrogen 0.005-0.015, calcium 0.001-0.010, iron and unavoidable impurities - the balance. When following relationships are fulfilled: Ti/48+Al/27-N/14 ≥ 0.6 x 10-3; Mn+5.0C ≥ 0.80; Ca/S ≥ 0.065, rolled iron has following characteristics: maximum degree of pollution with nonmetal inclusions, in particular sulfides, oxides, silicates, and nitrides, does not exceed 3 points for each type of inclusions; longitudinally uniform spheroidized structure composed of at least 60% grainy perlite; effective grain size 5-10 points; diameter 10-16 mm; carbon-free layer not exceeding 1.0% of diameter; cold setting value at least 1/3 height; throughout hardenability in circles up to 16 mm in diameter; point of maximum load not higher than 500 MPa; relative elongation at least 22%; and relative contraction at least 70%.

EFFECT: ensured optimal conditions for cold die forging of high-strength geometrically complex fastening members and simultaneously improved steel hardenability characteristics.

The invention relates to metallurgy, and more particularly to rolling production, and can be used in the manufacture of welded pipes for oil pipeline construction in seismic zones

FIELD: ferrous metallurgy.

SUBSTANCE: invention provides round-profiled iron smelted from alloyed steel composed of, wt %: carbon 0.06-0.11, manganese 0.30-0.9, silicon 0.001-0.15, boron 0.0005-0.0050, vanadium 0.005-0.08, aluminum 0.02-0.06, titanium 0.01-0.04, sulfur 0.005-0.020, nitrogen 0.005-0.015, calcium 0.001-0.010, iron and unavoidable impurities - the balance. When following relationships are fulfilled: Ti/48+Al/27-N/14 ≥ 0.6 x 10-3; Mn+5.0C ≥ 0.80; Ca/S ≥ 0.065, rolled iron has following characteristics: maximum degree of pollution with nonmetal inclusions, in particular sulfides, oxides, silicates, and nitrides, does not exceed 3 points for each type of inclusions; longitudinally uniform spheroidized structure composed of at least 60% grainy perlite; effective grain size 5-10 points; diameter 10-16 mm; carbon-free layer not exceeding 1.0% of diameter; cold setting value at least 1/3 height; throughout hardenability in circles up to 16 mm in diameter; point of maximum load not higher than 500 MPa; relative elongation at least 22%; and relative contraction at least 70%.

EFFECT: ensured optimal conditions for cold die forging of high-strength geometrically complex fastening members and simultaneously improved steel hardenability characteristics.

FIELD: ferrous metallurgy.

SUBSTANCE: invention provides round-profiled iron smelted from low-carbon steel composed of, wt %: carbon 0.17-0.25, manganese 0.30-0.65, silicon 0.01-0.17, sulfur 0.005-0.020, vanadium 0.005-0.07, niobium 0.005-0.02, calcium 0.001-0.010, iron and unavoidable impurities - the balance. When following relationships are fulfilled: 12/C-Mn/0.02 ≥ 27; 0.46 ≥ 6V+8Nb ≥ 0.22; Ca/S ≥ 0.065, rolled iron has following characteristics: maximum degree of pollution with nonmetal inclusions, in particular sulfides, oxides, silicates, and nitrides, does not exceed 3 points for each type of inclusions; longitudinally uniform spheroidized structure composed of at least 80% grainy perlite; effective grain size 5-10 points; diameter 10-25 mm; carbon-free layer not exceeding 1.5% of diameter; cold setting value at least 1/3 height; point of maximum load not higher than 550 MPa; relative elongation at least 20%; and relative contraction at least 60%.

EFFECT: ensured optimal conditions for cold die forging of high-strength geometrically complex fastening members and simultaneously ensured improved characteristics of in-process plasticity and low level of stray hardening.

FIELD: metallurgy; high-titanium-bearing foundry alloy production.

SUBSTANCE: the invention is dealt with the field of metallurgy, in particular, with production of the foundry alloy containing mainly titanium and also a small amount of other useful metals reduced from oxides of a charge together with the basic components of a foundry alloy. The method includes the following stages: after melting-down of the first portion of the charge representing an ilmenite concentrate formed on the rotating melt of the high-titanium-bearing foundry alloy and reduction by titanium and silicon of a part of oxides from the melted portion of ilmenite they use aluminum to reduce all oxides in a cinder melt. The obtained slag is added with the first portion of calcium oxide in the amount ensuring fluidity of the cinder. The second portion of the charge is introduced in the melt in the amount corresponding to the possibility of to reduce oxides by titanium. The produced titanium oxide is merged with the earlier produced cinder. A determined part of the produced melt in conditions of its rotation is poured out through a side tap hole. Using aluminum reduce titanium oxide from the merged cinder and the reduced titanium merge with the rest metal melt. In the formed final cinder enter the second portion of calcium oxide. A part of the produced foundry alloy is poured out through a side tap hole. Then a final cinder is also poured out and they feed a new portion of ilmenite onto the residue of the foundry alloy. The invention allows to reduce at least twice the power input used for reprocessing of the ilmenite concentrate, as in the process of reduction of the metals from oxides there are no endothermic reactions but exothermic reactions; to use ilmenite concentrates with a share of titanium oxide up to 45% and a strong metal reductant - aluminum, and also to realize a progressive technology of the liquid-phase reduction of metals from oxides in conditions of rotation of the melt by an electromagnetic field.

EFFECT: the invention allows to reduce at least twice the power input used for reprocessing of the ilmenite concentrate, to use ilmenite concentrates with a share of titanium oxide up to 45% and a strong metal reductant - aluminum, to realize a progressive technology of the liquid-phase reduction of metals from oxides.

5 cl, 1 ex, 1 dwg

FIELD: metallurgy; production of important rolled stock for oil-well tubing of increased service life.

SUBSTANCE: proposed method includes making steel of definite chemical composition in electric furnace, tapping metal from furnace into ladle, treatment of metal in ladle and teeming steel into ingot molds. Alloying with molybdenum is performed by introducing molybdenum-containing materials into furnace in making steel. After teeming, ingots are rolled, cooled and heated for rolling in preset temperature range and are subjected to preliminary and final deformation; process is completed by final cooling of rolled blanks to surrounding temperature.

EFFECT: improved strength characteristics and cold resistance of metal; enhanced reliability of metal products.

1 ex

Structural steel // 2251587

FIELD: metallurgy, in particular structural steel composition.

SUBSTANCE: claimed steel contains (mass %): carbon 0.42-0.54p; silicium 0.15-0.50; manganese 0.90-1.50; niobium 0.01-0.08; molybdenum 0.06-0.20; aluminum 0.005-0.060; titanium 0.019-0.045; sulfur 0.001-0.045; phosphorus 0.001-0.045; nitrogen less than 0.012; chromium, nickel and copper each not more than 0.30, and balance: iron. Steel of present invention is useful in production of pipelines for oil industry operating at temperature from 50°C to -10°C.

EFFECT: steel with optimum combination of strength and viscous properties.

2 tbl, 1 ex

FIELD: metalwork operating in cold climates at static loads.

SUBSTANCE: proposed iron-based cold-resistant alloy includes the following components, mass-%: titanium, 1-2; carbon, 0.009 max; silicon, 0.1 max; aluminum, 0.003 max; copper, 0.03 max; nickel, 0.2 max; the remainder being iron. Proposed alloy possesses high strength at retained ductility; embrittlement of this alloy at cooling to temperature below minus 78°C is excluded; content of carbon is considerably reduced due to increased content of titanium, thus enhancing resistance to cold.

EFFECT: enhanced efficiency; enhanced cold resistance.

1 dwg, 1 tbl

FIELD: ferrous metallurgy; motor-car industry; production of steels intended for manufacture of items of a complex configuration with the help of cold sheet stamping.

SUBSTANCE: the invention is pertaining to the field of ferrous metallurgy and motor-car industry, in particular, to methods of production of steels intended for manufacture by cold sheet stamping of items of a complex configuration, predominantly details for motor cars. The technical problem is to boost steel stamping, to improve the quality of a surface of a steel strip and hence to improve adhesion of a protective cover. The method includes a steel smelting, casting, hot rolling, strips reeling in rolls, a cold rolling, a recrystallization annealing and a temper rolling. The steel contains components in the following ratio (in mass %): Carbon - 0.002 - 0.008, silicon - 0.005-0.025, manganese - 0.05-0,20, phosphorus - 0.005-0.025, sulfur - 0.003-0.012, aluminum - 0.02-0.07, titanium - 0.02-0.05, niobium - 0.001 0.080, iron and imminent impurities - the rest. The hot rolling is completed at the temperature determined from the ratio: Tf.r≥ 7300 / (3.0-Ig [Nb] [C]) - 253, where Tf.r - temperature of the end of the rolling, °C; [Nb] and [C] - the shares of niobium and carbon in the steel accordingly in mass %, and the recrystallization annealing is carried out in a pusher-type furnace at the temperature assigned depending on the contents of niobium in steel according to the equation: Tan= (750+ 1850 [Nb]) ± 20, where Tan - a temperature of the thermal treatment, °C; [Nb] - the contents of niobium in the steel, in mass %.

EFFECT: the invention allows to boost the steel stamping, to improve the quality of the steel strip surface and adhesion of a protective cover.

4 ex, 1 tbl

FIELD: steel making.

SUBSTANCE: invention relates to such type of steel that is employed in welded structures such as gas conduits, petroleum pipelines, as well as in high-pressure vessels. Steel according to invention contains, wt %: C 0.02-0.10, Si up to 0.6, Mn 1.5-2.5, P up to 0.015, S up to 0.003, Ni 0.01-2.0, Mo 0.2-0.6, Nb below 0.010, Ti up to 0.030, Al up to 0.070, N up to 0.0060, Fe and unavoidable impurities - the rest, provided that parameter P = 2.7C+0.4Si+Mn+0.8Cr+0.45(Ni+Cu)+2V+Mo-0.5 is within a range of 1.9 to 3.5. Microstructure of steel is mainly composed of martensite and bainite. Steel sheet is manufactured by heating casting to at least Ac3, subjecting it to hot rolling, and cooling sheet at a rate 1°C/sec to temperature not exceeding 550°C. Sheet is further used to manufacture a tube. When laying multilayer welding joint, energy absorbed in the Charpy impact test at -40°C is at least 200 J.

EFFECT: achieved elongation strength at least 800 MPa.

21 cl, 1 dwg, 9 tbl, 5 ex

FIELD: metallurgy; production of low-alloyed cold-resistant steel for underwater sea gas lines at working pressure up to 19 Mpa working at low temperatures.

SUBSTANCE: proposed method includes production of steel blank, heating it to temperature above As3, deformation in controllable mode at specific reduction processes and at total reduction of 50-60% followed by controllable cooling; proposed steel has the following composition, mass-%: carbon, 0.05-0.9; manganese, 1.25-1.6; silicon, 0.15-0.30; chromium, 0.01-0.1; nickel, 0.3-0.6; molybdenum, 0.10-0.25; vanadium, 0.03-0.10; aluminum, 0.02-0.05; niobium, 0.01-0.06; copper, 0.2-0.4; calcium, 0.001-0.005; sulfur, 0.0005-0.005; phosphorus, 0.005-0.015; the remainder being iron; preliminary deformation of blanks is performed at temperature of 950-850°C at total reduction of 50-60%; then, blank is cooled down to temperature of 820-760°C at rate of cooling of 15°C/s on controllable cooling unit and final deformation is performed additionally at temperature of 770-740°C to required thickness of skelp at total reduction of 60-76%; further cooling is performed at higher rate of 35-55°C/s to temperature of 530-350°C, after which skelp is cooled in jacket to temperature of 150±20°C and then in the air. New stage of the proposed method makes it possible to manufacture tubes of 1067-1420 mm in diameter at thickness of walls of 24-40 mm which are used for sea gas pipe lines working at pressure of up to 19 Mpa.

EFFECT: enhanced strength, ductility and cold resistance; enhanced operational reliability; increased service life.

2 tbl, 1 ex

FIELD: metallurgy, namely cold resistant steels.

SUBSTANCE: cold resistant steel for machines and apparatuses, namely in gas- and oil production industry operating in condition of cold climate. Such steel contains, mass %: carbon, 0.15 - 0.22; manganese, 0.3 - 0.6; silicon, 0.15 - 0.40; vanadium, 0.08 -0.12; titanium, 0.001 - 0.040; niobium, 0.001 - 0.040; aluminum, 0.03 - 0.06; sulfur, 0.010 - 0.020; phosphorus, 0.010 - 0.020; cerium, 0.005 - 0.05; calcium, 0.001 - 0.01; barium, 0.001 - 0.01; iron, the balance.

EFFECT: improved strength and cold resistance of steel.

5 tbl

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