Production method of easily formable high-strength medium-thick steel plate

Abstract

The invention relates to a production method of an easily formable high-strength medium-thick steel plate. The method comprises the following process steps: converter steelmaking, ladle furnace refining, vacuum treatment vacuum treatment, continuous casting, heating, rolling, pre-straightening, on-line quenching and tempering heat treatment. The mass percent composition of the steel is as follows: C = 0.07-0.10, Si = 0.30-0.45, Mn = 1.45-1.55, P <= 0.015, S <= 0.005, Nb + V + Ti <= 0.10, Cr + Mo <= 0.3, Alt => 0.020, and Pcm <= 0.21. The Q550D steel plate with a thickness of 200mm produced by the method is good in cold bending, and the cold bending property of the steel plate real object meets the easily forming requirement of users; the yield ratio of the steel plate is smaller than 0.92, and the uniform elongation rate is larger than 8%, which meets the use requirements of relevant designs; the product of strength and elongation is increased by more than 35%, the capacity of resisting dynamic loading of the high strength steel plate is increased, and the equipment safety is improved; through hot charging and on-line quenching of the continuous casting, the production cost is reduced; and with the component design in which Pcm is smaller than 0.21%, the welding properties welding property of the high strength steel plate is improved.

Description

technical field [0001] The invention belongs to steelmaking technology, and is a production method of easy-to-form high-strength medium-thick steel plate. Background technique [0002] With the development of the metallurgical industry, the production of high-strength steel plates with a yield of more than 550MPa has undergone tremendous changes, from the traditional reheating quenching + tempering (ie RQ+T) process to TMCP, TMCP+T, DQ+T, Q+ P, Q+P+T, especially in recent years, the on-line direct quenching (Direct Quenching, DQ for short) process after rolling has made great progress and is widely used in the production of high-strength steel plates. [0003] Compared with the high-strength structural steel produced by other processes, the high-strength structural steel produced by the DQ process can greatly reduce the content of alloy elements and reduce the carbon equivalent under the condition of equivalent mechanical properties, improve the performance of welding and ot...

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Problems solved by technology

[0011] In short, the high-strength steel plate produced by the traditional direct quenching + tempering process (DQ+T) has the following disadvantages: the steel plate contains B elements, the hardenability of the steel plate is good, and the steel plate produced has high strength, high impact and low elongation. High, but the uniform elongation 0.96; the high yield ratio of the steel plate, it is difficult to meet the actual use requirements of the design; There is delamination in the steel plate; the steel plate is sampled according to the standard and the cold bending is qualified, but most of the wide cold bending and the actual steel plate are cracked, that is, the cold forming performance is poor; the cooling rate in the traditional DQ process after rolling the steel plate is > 35 ℃ / s, resulting in an uncontrolled yield-to-strength ratio

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