Structural steel S420ML medium and heavy plate and production method thereof

Abstract

The invention discloses a structural steel S420ML medium and heavy plate comprising chemical components of, by weight: 0.12 to 0.15% of C, 0.25 to 0.40% of Si, 1.45 to 1.55% of Mn, no more than 0.017% of P, no more than 0.003% of S, 0.015 to 0.035% of Als, 0.030 to 0.040% of Nb, 0.010 to 0.020% of Ti, 0.010 to 0.020% of Ni, and balance of Fe and residual elements. The carbon equivalent is represented by that: [Ceq=C+Mn / 6+(Cr+Mo+V) / 5+(Ni+Cu) / 15]<=0.41. The production method of the plate comprises processes of KR hot metal pretreating, converter smelting, argon-blowing treating, LF refining, VD refining, continuous casting, heating, controlled rolling and controlled cooling, and stack cooling. During the processes, a TMCP rolling technology and a steel plate stacking and sustained-cooling technology are adopted. With the method provided by the invention, components in S420ML can be ensured; contents of harmful elements such as P and S can be strictly controlled; a heating system in the steel rolling process is strictly controlled; during a rolling process, a finishing temperature, a self-tempering temperature and a cooling speed are strictly controlled; and methods such as a steel plate stacking and sustained-cooling technology are adopted. Therefore, performance indexes of a 20-50mm hot-rolled weldable fine-grain structural steel S420ML medium and heavy plate can reach required standards.

Description

technical field [0001] The invention belongs to the technical field of medium-thick steel plate production, and in particular relates to a structural steel S420ML medium-thick plate and a production method thereof. Background technique [0002] In the known technology, the production of traditional S420ML medium and thick plates is quite cumbersome, and the quality of the produced steel is not very good, which has a certain impact on the improvement of competition and income of enterprises. Contents of the invention [0003] In view of the above problems, the present invention provides a structural steel S420ML plate with high performance and easy production and a production method thereof. [0004] A medium and thick plate of structural steel S420ML, comprising the following chemical composition in mass percentage (unit, wt%): C: 0.12~0.15, Si: 0.25~0.40, Mn: 1.45~1.55, P≤0.017, S≤0.003, Als : 0.015~0.035, Nb: 0.030~0.040, Ti: 0.010~0.020, Ni: 010~0.020, others are Fe an...

AI Technical Summary

Problems solved by technology

[0002] In the known technology, the production of traditional S420ML medium and thick plate is quite cumbersome, and the quality of the steel produced is not very good, which has a certain impact on the improvement of competition and income of enterprises

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