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Method for improving low-alloy high-strength steel structure and performance

A high-strength steel and low-alloy technology, which is applied in the fields of improving the microstructure of low-alloy high-strength steel and improving its mechanical properties, and improving the strength and toughness of low-alloy high-strength steel. It can solve the problems of increased deformation resistance and shortened workpiece life, and achieve increased strength. , microstructure and mechanical properties improvement, and the effect of promoting ferrite transformation

Inactive Publication Date: 2008-04-09
TSINGHUA UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, as the grains are further refined, the life of the workpiece is shortened due to the increase in deformation resistance, and it is difficult for this method to play a greater role in actual production.

Method used

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  • Method for improving low-alloy high-strength steel structure and performance

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] Put the low-alloy high-strength steel plate with a carbon content of 0.08%, a sulfur content of 0.0008%, and a vanadium content of 0.005% into a vacuum induction furnace, add a certain amount of sulfur and vanadium iron, and remelt the obtained sulfur and vanadium The contents are 0.04% and 0.10%, respectively. After hot rolling, heat it to 1250°C at a speed of 10°C / s and keep it warm for 3 minutes, then air-cool to 900°C. Deformation rate Apply 30% compression deformation, then air-cool to 650°C for 5 minutes, and finally air-cool to room temperature. Using a metallographic microscope to inspect the deformation, the volume fraction of intragranular and grain boundary ferrite in the sample after air cooling increased from the original 1.3% and 13.5% to 18.7% and 26.2% (as shown in Figure (a) (b)) , the hardness increased from 21.7HRC to 32.8HRC, and the impact absorption energy increased from 31J to 57J.

Embodiment 2

[0022] Put the low-alloy high-strength steel plate with a carbon content of 0.09%, a sulfur content of 0.0009%, and a vanadium content of 0.01% into a vacuum induction furnace, add a certain amount of sulfur and ferrovanadium, and remelt the obtained sulfur and vanadium The contents are 0.045% and 0.12%, respectively. After hot rolling, it is heated to 1200°C at a speed of 8°C / s and kept for 5 minutes, then air-cooled to 900°C. -1 Apply 20% compression deformation at the deformation rate, then air-cool to 650°C for 1 min, and finally air-cool to room temperature. Use a metallographic microscope to check the volume fraction of intragranular and grain boundary ferrite in the sample after air cooling from the original 1.5% and 9.4% to 12% and 21.8%, the hardness increased from 22.5HRC to 30.4HRC, and the impact absorption energy Increased from 30.5J to 52J.

Embodiment 3

[0024] Put a low-alloy high-strength steel plate with a carbon content of 0.09%, a sulfur content of 0.0007%, and a vanadium content of 0.003% into a vacuum induction furnace, add a certain amount of sulfur and vanadium iron, and remelt the obtained sulfur and vanadium The contents are 0.03% and 0.1%, respectively. After hot rolling, it is heated to 1300°C at a speed of 8°C / s and held for 3 minutes, then air-cooled to 910°C. -1 Apply 30% compression deformation at the deformation rate, then air-cool to 640°C for 10 minutes, and finally air-cool to room temperature. Using a metallographic microscope to check the deformation, the volume fraction of intragranular and grain boundary ferrite in the sample after air cooling increased from 0.8% and 14% to 15.2% and 28%, the hardness increased from 23.6HRC to 31.2HRC, and the impact absorption energy Increased from 28J to 58.7J.

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Abstract

The invention relates to a method to improve the structure and performance of low alloy high strength steel, belonging to the field of steel material. The invention re-smelts industrialized low alloy high strength steel by using a vacuum induction electric oven to increase the sulfur and vanadium content, leads MnS and V(C,N) to be separated out in a relatively low temperature for a proper time after austenitizing, and conduct proper stress on the austenite area to deform, cool down to ferrite and stay in such temperature for a proper time, and then air-cool down to the room temperature, the process improves the structure of low alloy high strength steel, levels up the mechanical performance. The leaching volume in the invention can be easily controlled, austenite deforming process is easy and practical and cheap, which can be directly applied to the improvement of the structure and performance of the low alloy high strength steel, in particular to increase the ferrite volume in the crystal and thin the structure of the whole steel. The increase in intention and tenacity widens the application of low alloy high strength steel to a great extent.

Description

technical field [0001] The invention belongs to the field of iron and steel materials, and relates to a method for improving the microstructure and mechanical properties of low-alloy high-strength steel, which is mainly used for improving the strength and toughness of low-alloy high-strength steel. Background technique [0002] The development of widely used low-alloy high-strength structural steel plates has been highly valued by countries all over the world. Microstructure refinement is the only way to simultaneously improve the strength and toughness of steel without significantly changing the chemical composition. At present, ultra-fine-grained steel with micron-sized grains has been successfully obtained through various technological means at home and abroad, among which the controlled rolling and controlled cooling process is the most commonly used effective method for grain refinement. However, as the grains are further refined, the life of the workpiece is shortened...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C33/04C22C38/12C21D8/00
Inventor 杨志刚张弛陶鹏
Owner TSINGHUA UNIV
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