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Low-carbon steel and preparing method thereof

A low-carbon steel and matrix technology, which is applied in the field of low-carbon steel and its preparation, can solve the problems of low plasticity and toughness, sacrificing plasticity and toughness of low-carbon steel, and cannot guarantee the safety and reliability of engineering applications, and achieves improved strength and strength. improved effect

Active Publication Date: 2019-12-10
TANGSHAN GANGLU IRON & STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] However, the traditional methods of strengthening low-carbon steel, such as quenching treatment or adding alloy elements, inevitably sacrifice the plasticity and toughness of low-carbon steel, and the low plasticity and toughness cannot guarantee the safety and reliability of its engineering application

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] This embodiment provides a low-carbon steel, including a matrix, the matrix is ​​composed of the following chemical components by mass percentage: 0.17-0.22% carbon, 0.19-0.25% silicon, 0.34-0.45% manganese, 0.03-0.05% phosphorus, Sulfur is 0.034-0.045%, and the balance is iron; the low-carbon steel is ferrite grain obtained from the matrix. In this embodiment, preferably, the matrix is ​​composed of the following chemical components by mass percentage: 0.17% carbon, 0.19% silicon, 0.34% manganese, 0.03% phosphorus, 0.034% sulfur, and the balance is iron. The ferrite grains are rod-shaped and have a gradient structure that decreases continuously from the core to the surface in the radial direction. The size of the ferrite grains decreases continuously in the radial direction from 13.2 μm at the core to 5.1 μm at the surface. The yield strength of the low carbon steel is 418-556MPa, the failure elongation is 15-20%, and the static toughness is 86-109MJ / m3.

[0020] Thi...

Embodiment 2

[0025] In this example, the low-carbon steel dog-bone rod-shaped sample was kept at 700°C for 2 hours to obtain a low-carbon steel with a uniform composition and a coarse-grained structure. The coarse-grained sample was subjected to torsional deformation treatment using a torsion testing machine, and the torsional deformation rate was maintained at 120 degrees / minute, control the amount of deformation (torsion angle) to 540 degrees, and then place the low carbon steel twisted and deformed at room temperature in a vacuum thermal annealing furnace for annealing treatment, the vacuum degree is 10 -1 Pa, the temperature is 650°C, keep warm for 30 minutes and then cool to room temperature with water.

[0026] Using EBSD to observe the microstructure of the sample, the low carbon steel prepared by the above method is a gradient structure in which the ferrite grain size continuously decreases from 16.5 μm at the center to 7.2 μm at the surface along the radial direction of the rod-sha...

Embodiment 3

[0028] In this example, the low-carbon steel dog-bone rod-shaped sample was kept at 700°C for 2 hours to obtain a low-carbon steel with a uniform composition and a coarse-grained structure. The coarse-grained sample was subjected to torsional deformation treatment using a torsion testing machine, and the torsional deformation rate was maintained at 120 degrees / minute, control the amount of deformation (torsion angle) to 540 degrees, and then place the low-carbon steel twisted and deformed at room temperature in a vacuum thermal annealing furnace for annealing treatment. Minutes later the water was cooled to room temperature.

[0029] The microstructure of the sample was observed by EBSD. The low-carbon steel prepared by the above method is a gradient structure in which the ferrite grain size continuously decreases from 13.2 μm at the center to 5.1 μm at the surface along the radial direction of the rod-shaped sample. . Tensile tests at room temperature were performed on an In...

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Abstract

The invention relates to the technical field of material preparation, in particular to low-carbon steel and a preparing method thereof. The low-carbon steel includes a matrix, and the matrix is composed of the following chemical components including, by mass, 0.17%-0.22% of carbon, 0.19%-0.25% of silicon, 0.34%-0.45% of manganese, 0.03%-0.05% of phosphorus, 0.034%-0.045% of sulfur and the balanceiron; and the low-carbon steel is ferrite grains obtained from the matrix. The method includes the following steps of conducting preservation on a low-carbon steel rod-shaped sample at 650-750 DEG C for 1.5-2 h to obtain coarse-grain structure low-carbon steel with uniform compositions; using a torsion tester to conduct torsional deformation treatment on the obtained coarse-grain structure low-carbon steel; and placing the low-carbon steel obtained by indoor temperature torsional deformation into a vacuum thermal annealing furnace for annealing treatment. By means of the low-carbon steel and the preparing method, the strength of the obtained low-carbon steel is improved by 200 MPa, and meanwhile, the considerable failure elongation and static toughness are maintained.

Description

technical field [0001] The invention relates to the technical field of material preparation, in particular to a low-carbon steel and a preparation method thereof. Background technique [0002] Low-carbon steel has excellent properties such as low cost, high plasticity, and high toughness, and is an important material for preparing structural parts such as bolts, bearings, and rivets. Low-carbon steel materials widely used at present, such as Q235 and T20, have a yield strength of 200-400 MPa and an elongation at failure of 20-30%. However, the low strength of low carbon steel limits its wide application. The development of technology requires that the prerequisite for the wide application of low carbon steel is to increase its strength while maintaining its plasticity and toughness. [0003] However, the traditional methods of strengthening low-carbon steel, such as quenching treatment or adding alloy elements, inevitably sacrifice the plasticity and toughness of low-carbo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/02C22C38/04C22C38/60C21D8/06C21D1/26C21D1/773
CPCC21D1/26C21D1/773C21D8/065C21D2211/005C22C38/02C22C38/04C22C38/60
Inventor 石银冬王丽娜张喜亮王小铭罗小钧
Owner TANGSHAN GANGLU IRON & STEEL
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