Method of production of steel sheet products from low-carbon or low-carbon low-alloy steel (options)

 

The invention relates to metallurgy, and more specifically to the production of sheet steel, and may be used in the manufacture of hot-rolled sheets of low-carbon or low-carbon low-alloy steels intended for cold forming, deep drawing, extrusion and so on, the Technical result of the invention is to obtain a hot-rolled sheets of low-carbon or low-carbon low-alloy steel with a minimum anisotropic mechanical properties and high ductility, which allows the manufacture of these products by cold plastic deformation, including deep drawing, extrusion, backward extrusion. The technical result is achieved by the fact that the forged slab section 140400 mm of steel 11JUA after heating to 1150With subjected to rolling along the axis of the slab with a compression of 60%. The temperature of the end of the rolling was 980C. the resulting piece is cut on the in, cooled in air to 550C, heated to 1080With and rolled in a transverse direction relative to the rolling of the original slab leaves elsinoe the degree of deformation in the longitudinal direction to the degree of deformation in the transverse direction are connected by dependency 0,51.5 and equal to 0.88. Cooled to room temperature, hot-rolled sheet subjected to quenching from a temperature of 950With cooling in water and subsequent high holidays in the cover furnace at 680With aged 10 hours, after which your batch metal cooled in air to room temperature. In the first and second embodiments of the invention are rolling first lengthwise, then in the transverse direction, or first - cross, and then in the longitudinal direction. In the third embodiment of the invention, the direction of hot deformation can be changed in the following sequence: hot rolling of the slab are in the longitudinal direction, and the hot rolling of the received burst is a first cross, then in the longitudinal direction, with the degree of deformation associated dependence 0,51,5 (2), where- the ratio of the total degree of deformation of the slab and roll in the longitudinal direction to a degree of deformation of the roll in the transverse direction; and hot rolling the slab conduct research Institute, the degree of deformation is associated with dependence 0,51,5 (3), wherethe extent of deformation of the roll in the longitudinal direction to the total degree of deformation of the slab and roll in the transverse direction. 3 N. and 9 C.p. f-crystals, 1 table.

The invention relates to metallurgy, and more specifically to the production of sheet steel, and may be used in the manufacture of hot-rolled sheets of low-carbon or low-carbon low-alloy steels intended for cold forming, deep drawing, extrusion and so on

There is a method of production of steel sheet for deep drawing, including hot rolling, accelerated cooling, winding the strip into a roll, the roll unwinding, cutting it into sheets and normalization, which is carried out in two stages: first at a temperature AU3+(30-50)Since, then, in the interval between the critical points AU1and AU3. The result is a metal structure that is favorable for the subsequent cold the processing and reduction of energy consumption (RF Patent No. 2133284, IPC C 21 D 8/04, publ. 20.07.1999,).

In the method of hot rolling a steel strip deformation of the workpiece takes place by elongation in one direction - along the strip, resulting in low-carbon and low-carbon low-alloy steel is formed strachocina distribution of nonmetallic inclusions and, as a rule, strachocina ferritic-pearlitic structure, which leads to a significant reduction in ductility of the steel sheet in a direction across the rolling.

The closest analogue is a method for the production of thick steel sheets, which includes the receipt of the slab from the ingot hot plastic deformation and subsequent hot rolling, consisting of three stages. In the first stage, the slabs are rolled along the axis to align thickness. In the second stage, after the alignment, after the first 2-4 passages, the slab is turned 90and rolled across its length to obtain the necessary width of the sheet. In the third stage of rolling thunder again turn 90and rolled it to get the required thickness and length. This method of rolling reduces the anisotropic and improves the mechanical and technological properties sheet storiestoy steel subjected to quenching with high holiday (N. And.Sheftel. “The technology of steel production.” M.: metallurgy, 1976, S. 38-49; 394-398 - prototype).

The disadvantage of this method is the lack of regulation of the degree of deformation during rolling of the slab in the longitudinal and transverse directions, which can lead to poor reproducibility of the size and shape of the grains after hot rolling and, as a consequence, a high anisotropy of the mechanical properties of the sheet along and across rolling.

The problem to which the invention is directed, is to obtain a hot-rolled sheets of low-carbon or low-carbon low-alloy steel with a minimum anisotropic mechanical properties and high ductility, which allows the manufacture of these products by cold plastic deformation, including deep drawing, extrusion, backward extrusion.

The technical result of the invention is to achieve qualitative indicators of the sheet, formulated in the problem statement.

This technical result is achieved in that in the method of production of steel sheet products from low-carbon or low-carbon low-alloy steels, including the manufacture of the slab, hot rolling the steel at a 1250-11001,5 (1), wherethe extent of deformation in the longitudinal direction to the degree of deformation in the transverse direction.

While rolling are first in the longitudinal and then in the transverse direction or first - cross, and then in the longitudinal direction.

As a variant, this technical result is achieved in that in the method of production of steel sheet products from low-carbon or low-carbon low-alloy steels, including the manufacture of the slab, hot rolling the steel at a 1250-1100With alternately in the longitudinal and transverse directions, cooling, hardening and high-temperature tempering, according to the invention after the first rolling slab spend the cooling roll up to 500-600S, after which the roll is heated to a temperature of hot rolling and carry out the deformation in the direction of perpendic the directions are 30-85% and associated dependence (1).

In this case, as in the first embodiment, in the second embodiment of the invention the rolling are first in the longitudinal and then in the transverse direction or first - cross, and then in the longitudinal direction.

In the third version of this technical result is achieved in that in the method of production of steel sheet products from low-carbon or low-carbon low-alloy steels, including the manufacture of the slab, hot rolling the steel at a 1250-1100With alternately in the longitudinal and transverse directions, cooling, hardening and high-temperature tempering, according to the invention after the first rolling slab spend the cooling roll up to 500-600S, after which the roll is heated to a temperature of hot rolling and carry out the deformation of the roll in two stages, changing its direction at each stage 90in relation to the previous one, in this case the degree hot deformation in both longitudinal and transverse directions are 30-85%.

In the third embodiment of the invention, the direction of hot deformation can be changed in the following sequence:

hot rolling of the slab are in the longitudinal direction, and hot rolling the obtained roll - �"https://img.russianpatents.com/chr/8804.gif">1,5 (2), where’ is the ratio of the total degree of deformation of the slab and roll in the longitudinal direction to a degree of deformation of the roll in the transverse direction;

or hot rolling of the slab are in the transverse direction, and a hot rolling roll are first in the longitudinal and then in the transverse direction, while the degree of deformation associated dependence 0,51,5 (3), where’ is the ratio of the degree of deformation of the roll in the longitudinal direction to the total degree of deformation of the slab and roll in the transverse direction.

In these dependencies, (2) and (3) the total degree of deformation is determined by the formula:

wherethe product of n factors,1the degree of deformation on the i-th stage of rolling out the number n of pochatok, which is determined by the total degree of deformation.

In all three versions of the invention, the slab is made or forging or hot rolling, or casting in moulds or on the installation of continuous casting.

p>When cooling roll temperature end of rolling slab, component 920-970With up to ambient temperature or up to 500-600With the formation of ferrite-pearlite structure, which initiates an additional refinement of austenite during subsequent heating of the roll to a temperature of the second rolling and in the passing of a primary recrystallization during the rolling and after its completion. Along with the specified intermediate cooling up to 500-600To help conserve energy during subsequent heating to a temperature rolling.

Regulation of deformation within 30-85% provides grinding grains of austenite by recrystallization during deformation along and across the axis of the original slab, as well as during cooling of the sheets after the last rolling and, as a consequence, obtaining crushed ferrite-pearlite structure in the finished sheet with equiaxial grain free ferrite in the structure, which contributes to the achievement of the isotropy of the mechanical properties of the sheet.

When performing correlations relating the amount of deformation along and across the axis of the original slab, the described dependence is ical inclusions in the longitudinal and transverse directions, eliminates strokefest microstructure that provides the after quenching and high holiday isotropic hot-rolled sheet, characterized by high plasticity.

Below are examples of the implementation of the proposed method.

Example 1. Forged slab section 140400 mm of low-carbon low-alloy steel grade 11JUA containing 0,11% carbon and 0.06% aluminum, after heating to 1150With subjected rolling along the axis of the slab with a compression of 60%. The temperature of the end of rolling in this case amounted to 980C. the resulting piece cut on the in. The cooled in air to a temperature of 550With, after which it was heated to 1080With and laminated in the transverse direction relative to the rolling of the original slab sheets of a thickness of 18 mm with a compression 68%. The temperature of the end of the rolled sheet amounted to 940C. the ratio of the degree of deformation in the longitudinal direction to the degree of deformation in the transverse direction is equal to 0.88. Cooled to room temperature, hot-rolled sheets were subjected to the hardening temperature of 950With cooling in water and the following is the lia cooled in air to room temperature. Mechanical properties of sheets made consistent prokatami in the longitudinal and transverse directions, on the specified modes shown in the table in comparison with the properties of sheets made three consecutive prokatami slab of steel 11JUA after pre-heating to 1150With (prototype). The first rolling was carried out in the longitudinal direction with compression 20%, the second rolling piece was performed in the transverse direction by compression of 30% and the third rolling in the longitudinal direction on the sheet thickness of 18.0 mm, with a deformation rate of 77%. The total longitudinal extent of deformation in this case is equal to 82%. Between prokatami special cooling was not performed. The temperature of the end of the rolling was 980C. After air cooling the hot rolled sheets were subjected to quenching from 950With water and subsequent high tempering at 680With exposure of 10 hours. The extent of the total longitudinal deformation to the extent of transverse strain,’ when it was 2.7.

Example 2. Forged slab section 140400 mm of low-carbon low-alloy steel grade 11JUA the CA rolling in this case amounted to 960C. the resulting piece cut on the in. The cooled in air to room temperature, then heated to 1100With and laminated in the transverse direction relative to the longitudinal axis of the slab sheets of a thickness of 21 mm with compression 65%. The temperature of the end of the rolled sheet amounted to 960C. the ratio of the degree of deformation in the longitudinal direction to the degree of deformation in the transverse directionequal to 0.88.

Cooled in air to room temperature, hot-rolled sheets were subjected to the hardening temperature of 950With cooling in water and subsequent high tempering at 680With aged 10 h and cooled in air to room temperature. Mechanical properties of sheets made consistent prokatami in the longitudinal and transverse directions on the processing conditions shown in the table.

Example 3. Forged slab of steel 11JUA thickness of 120 mm after heating to 1150With laminated in the transverse direction by compression of 50%. The temperature of the end of the rolling was 980C. the resulting roll was cut into pieces �/img.russianpatents.com/chr/176.gif">With laminated in the longitudinal direction relative to the axis of the original slab with a compression of 50%, and then turned 90in the plane rolled and laminated in a transverse direction relative to the axis of the original slab with compression 38% of the sheet thickness of 18.5 mm total degree of deformation in the two pochatok in the transverse directionsumwas 69%. In this respect, the degree of deformation of the roll in the longitudinal direction to the total degree of deformation of the slab and roll in the transverse directionamounted to 0.72. The mechanical properties of the finished sheet after quenching from 950With water and high tempering at 680With aged 8 hours and subsequent cooling to room temperature is shown in the table.

Example 4. Concast slab thickness of 150 mm of steel grade 20 after being heated to 1170With laminated by compression of 55% in the longitudinal direction. The temperature of the end of the rolling amounted to 970With the Received burst cut into billets and cooled to a temperature of 600C. Then blanks from a roll from the previous the y axis of the original slab with compression 65%, then made the turn in the plane of the rolling 90and laminated in the longitudinal direction relative to the longitudinal axis of the original slab with deformation rate of 49% on the sheets with thickness of 12 mm, the total degree of deformationsumtwo pochatok in the longitudinal direction was 77%. The ratio of total deformation in the longitudinal direction to the degree of deformation in the transverse direction' well 1,18. The temperature of the end of the rolling amounted to 940C. After cooling to room temperature, the sheet was heated to 900C and subjected to normalization and then - high vacation at 700With aged 6 hours; your batch was cooled under a muffle the cover furnace to 500S, after which the retort was removed and the cooling continued in air to room temperature. Mechanical properties of sheets with thickness of 12 mm, produced according to the above-described technology with two longitudinal prokatami and one rolling in the transverse direction shown in the table in comparison with the mechanical properties of sheets made of this steel, obtained by rolling continuously cast slab in longitudinal neatly piece in the longitudinal direction relative to the longitudinal axis of the original slab with compression 82% (prototype). The total degree of deformation in the longitudinal direction of thesumwas 86%; the ratio of total deformation in the longitudinal direction to the degree of deformation in the transverse direction' well 2,16.

Claims

1. Method of production of steel sheet products from low-carbon or low-carbon low-alloy steels, including the manufacture of the slab, hot rolling the steel at a 1250-1100With alternately in the longitudinal and transverse directions, cooling, hardening and high-temperature tempering, characterized in that after the first rolling slab spend the cooling roll to the ambient temperature, after which the roll is heated to a temperature of hot rolling and carry out the deformation in the direction perpendicular to the first rolling, while the degree of hot deformation in both longitudinal and transverse directions are 30-85% and associated dependence 0,51,5, wherethe extent of deformation in the longitudinal direction to the degree of deformation in the transverse direction.

2. Spooo p. 1 or 2, wherein the hot rolling are first in the longitudinal and then in the transverse direction.

4. The method according to p. 1 or 2, characterized in that the hot rolling are first to cross, and then in the longitudinal direction.

5. Method of production of steel sheet products from low-carbon or low-carbon low-alloy steels, including the manufacture of the slab, hot rolling the steel at a 1250-1100With alternately in the longitudinal and transverse directions, cooling, hardening and high-temperature tempering, characterized in that after the first rolling slab spend the cooling roll up to 500-600S, after which the roll is heated to a temperature of hot rolling and carry out the deformation in the direction perpendicular to the first rolling, while the degree of hot deformation in both longitudinal and transverse directions are 30-85% and associated dependence 0,51,5, wherethe extent of deformation in the longitudinal direction to the degree of deformation in the transverse direction.

6. The method according to p. 5, characterized in that the slab is made or forging or hot rolling, is in the transverse direction.

8. The method according to p. 5 or 6, characterized in that the hot rolling are first to cross, and then in the longitudinal direction.

9. Method of production of steel sheet products from low-carbon or low-carbon low-alloy steels, including the manufacture of the slab, hot rolling the steel at a 1250-1100With alternately in the longitudinal and transverse directions, cooling, hardening and high-temperature tempering, characterized in that after the first rolling slab spend the cooling roll up to 500-600S, after which the roll is heated to a temperature of hot rolling and carry out the deformation of the roll in two stages, changing its direction at each stage 90in relation to the previous one, in this case the degree hot deformation in both longitudinal and transverse directions are 30-85%.

10. The method according to p. 9, characterized in that the slab is made or forging or hot rolling, or casting.

11. The method according to p. 9 or 10, characterized in that the hot rolling of the slab are in the longitudinal direction and a hot-rolling roll are first cross, then in the longitudinal direction, with the degree of deformation associated dependence 0,5- the ratio of the total degree of deformation of the slab and roll in the longitudinal direction to a degree of deformation of the roll in the transverse direction, and the total degree of deformation,sumthat is determined by the formula

wherethe product of n factors;

i- the degree of strain in the i-th stage of rolling out the number n of pochatok, which is determined by the total degree of deformation.

12. The method according to p. 9 or 10, characterized in that the hot rolling of the slab are in the transverse direction, and a hot rolling roll are first in the longitudinal and then in the transverse direction, while the degree of deformation associated dependence 0,51,5, wherethe extent of deformation of the roll in the longitudinal direction to the total degree of deformation of the slab and roll in the transverse direction, and the total degree of deformation,sumthat is determined by the formula

 

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FIELD: metallurgy, production of rolled steel.

SUBSTANCE: the invention is pertaining to the field of metallurgy, production of rolled steel, in particular, to methods of production of cold rolled steel sheets with the high drawing properties for a cold forming of details of cars bodies. The technical problem being solved by the invention consists in improvement of the quality of a cold rolled sheet steel. The method provides for hot rolling of continuously-cast low-carbon steel slabs, etching treatment, multirun cold rolling with total relative reduction of no less than 75 %, a recrystallization annealing in the following mode: a heating at an average speed of 70-80°C/h up to temperature of 490-510°C, a repeated heating at an average speed of 3-4 °C/h up to the intermediate temperatures of 540-560 °C/h and the final heating at an average speed of 50 - 55°C/h up to the annealing temperature of 700-720 °C, at which the steel rolls are kept for 12-18 h. Upon termination of keeping the rolls at the annealing temperature they are cooled at the rate of 19-21 °C/h up to the temperatures not exceeding 690 °C. At that the continuously cast low-carbon steel slabs have the following chemical composition (in mass %): 0.025-0.050 - carbon, 0.003-0.010 - silicon, 0.12-0.19 - manganese, 0.02-0.05 - aluminum, no more than 0,011 - nitrogen, the rest - iron and impurities.

EFFECT: the invention ensures improvement of the quality of a cold rolled sheet steel.

3 cl, 5 ex, 3 tbl

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