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A low-alloy steel hot-rolled steel strip with a tensile strength above 500mpa and its preparation method

A low-alloy steel and tensile strength technology is applied in the field of low-alloy steel hot-rolled steel strip and its preparation, and can solve the problems of reducing the properties of each phase of the steel strip, rapidly decreasing the temperature of the steel strip, reducing the elongation of the steel strip, and the like. To achieve the effect of improving the purity of molten steel, increasing the temperature of the molten steel, and improving the center segregation

Active Publication Date: 2017-09-19
SHANDONG IRON & STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the water laminar cooling method, the temperature of the steel strip drops rapidly, the elongation of the steel strip is reduced, and Widmanstatten structure is prone to appear, which reduces the performance of each phase of the steel strip.

Method used

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  • A low-alloy steel hot-rolled steel strip with a tensile strength above 500mpa and its preparation method
  • A low-alloy steel hot-rolled steel strip with a tensile strength above 500mpa and its preparation method

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0026] 1. The chemical composition percentage of steel is as follows:

[0027] C: 0.19%, Si: 0.32%, Mn: 1.13%, P: 0.025%, S: 0.015%, V: 0.022%, and the rest is Fe element and unavoidable impurities.

[0028] 2. The production process of low-alloy hot-rolled steel strip, taking the specification of 3.25mm×374mm as an example:

[0029] (1) Production process

[0030] Hot metal pretreatment-BOF-ladle bottom blowing argon-CC-slab heating-rough rolling-finish rolling-coiling;

[0031] (2) Preparation process

[0032] The molten iron pretreatment controls the sulfur content of the molten iron below 0.025%. The basicity of converter slag is controlled at 3.0-3.5, and the steel discharge temperature is based on the carbon drawing temperature. When the carbon drawing temperature is equal to the steel discharge temperature, the steel discharge operation can be carried out. , Strictly control the slag situation in the tapping process, and control the composition of the end point of c...

Embodiment 2

[0037] 1. The chemical composition percentage of steel is as follows:

[0038] C: 0.14%, Si: 0.28%, Mn: 1.14%, P: 0.027%, S: 0.018%, V: 0.025%, and the rest is Fe element and unavoidable impurities.

[0039] 2. The production process of low-alloy hot-rolled steel strip, taking the specification of 3.35mm×374mm as an example:

[0040] (1) Production process

[0041] Hot metal pretreatment-BOF-ladle bottom blowing argon-CC-slab heating-rough rolling-finish rolling-coiling;

[0042] (2) Preparation process

[0043] The molten iron pretreatment controls the sulfur content of the molten iron below 0.025%. The basicity of converter slag is controlled at 3.0-3.5, and the steel discharge temperature is based on the carbon drawing temperature. When the carbon drawing temperature is equal to the steel discharge temperature, the steel discharge operation can be carried out. , Strictly control the slag situation in the tapping process, and control the composition of the end point of c...

Embodiment 3

[0048] 1. The chemical composition percentage of steel is as follows:

[0049] C: 0.17%, Si: 0.28%, Mn: 1.12%, P: 0.029%, S: 0.017%, V: 0.023%, and the rest is Fe element and unavoidable impurities.

[0050]2. The production process of low-alloy hot-rolled steel strip, taking the specification of 2.2mm×302mm as an example:

[0051] (1) Production process

[0052] Hot metal pretreatment-BOF-ladle bottom blowing argon-CC-slab heating-rough rolling-finish rolling-coiling;

[0053] (2) Preparation process

[0054] The molten iron pretreatment controls the sulfur content of the molten iron below 0.025%. The basicity of converter slag is controlled at 3.0-3.5, and the steel discharge temperature is based on the carbon drawing temperature. When the carbon drawing temperature is equal to the steel discharge temperature, the steel discharge operation can be carried out. , Strictly control the slag situation in the tapping process, and control the composition of the end point of con...

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Abstract

The invention discloses a low-alloy steel hot-rolled steel strip with a tensile strength above 500 MPa, the chemical composition of which includes: C: 0.14%-0.22%, Si: 0.05%-0.40%, Mn: 0.90%-1.30 %, S: ≤0.035%, P: ≤0.035%, V: 0.020%‑0.040%, and the rest are iron and unavoidable impurities. When the present invention produces the hot-rolled steel strip, on the basis of the original process equipment, instead of using the water-cooling process, it adopts vanadium-nitrogen alloy for micro-alloying to improve the performance of the steel strip. Compared with Q345B of the same level, the yield strength is increased by about 40 MPa, The tensile strength is increased by about 60MPa, and the elongation is increased by about 50%. At the same time, the central segregation of the continuous casting slab is improved, the internal structure of the steel strip is improved, and the performance of the strip strip is stabilized.

Description

technical field [0001] The invention belongs to the technical field of iron and steel, and in particular relates to a low-alloy steel hot-rolled strip with a tensile strength above 500 MPa and a preparation method thereof. Background technique [0002] Most iron and steel enterprises improve the mechanical properties of the steel strip mainly through the water laminar flow cooling method, which can not only greatly improve the mechanical properties of the steel strip, but also save production costs. However, due to the laminar water cooling method, the temperature of the steel strip drops rapidly, the elongation of the steel strip is reduced, and Widmanstatten structure is prone to appear, which reduces the properties of each phase of the steel strip. [0003] The Widmanstatten structure is due to the fact that when the heating temperature is too high and cooled at a faster rate, pro-eutectoid ferrite or pro-eutectoid cementite grows from the austenite grain boundary along a...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C22C38/12C21D8/02
Inventor 郝帅袁鹏举刘曌娲李四军孙建卫王孝科张宗峰
Owner SHANDONG IRON & STEEL CO LTD