A production method of easy-to-form high-strength medium-thick steel plate

Abstract

The invention relates to a production method of an easily-shaped high-strength medium-thickness steel plate, which comprises the processing steps of converter steelmaking, ladle furnace refinement, vacuum treatment, continuous casting, heating, rolling, pre-straightening, on-line quenching and tempering heat treatment. The steel comprises the following components in percentage by mass: 0.07-0.09% of C, 0.15-0.30% of Si, 1.60-1.90% of Mn, no more than 0.015% of P, no more than 0.005% of S, no more than 0.12% of Nb+V+Ti, no more than 1.20% of Cr+Mo, no less than 0.020% of Alt, no more than 0.60% of CEV and no more than 0.27% of Pcm. The Q890E steel plate produced by the method has good 120mm-wide cold bending property, and the real cold bending property of the steel plate meets the requirements of users for easy shaping; the yield ratio of the steel plate is less than 0.92, and the uniform elongation rate is more than 8%, thus meeting the use requirements of related designs; the product of strength and elongation is increased by more than 35%, the dynamic load resistance of the high-strength steel plate is increased, and the safety of equipment is enhanced; the hot charging and on-line quenching of a continuous casting billet reduce the production cost; and the component design (the percentage of Pcm is no more than 0.27%) increases the welding property of the high-strength steel plate.

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 elongation of the steel plate composition is less than 7%, the steel plate yield ratio is greater than 0.96; the steel plate yield ratio is high, and it is difficult to meet the actual design requirements. Requirements for use; the uniform elongation of the steel plate is low, and the fracture of the steel plate is delaminated during the tensile test. The user thinks that the steel plate has a delamination phenomenon; the steel plate is sampled according to the standard for cold bending inspection, but most of the wide cold bending and the actual steel plate are cracked. That is, the cold-bending formability is poor; the cooling rate in the traditional DQ process after steel rolling is >35°C / s, resulting in uncontrolled yield ratio

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