Production method of low-carbon equivalent super-thick steel plate Q460E

Abstract

The invention provides a production method of low-carbon equivalent super-thick steel plate Q460E. The steel comprises, by mass, 0.04-0.07 part of C, 0.15-0.35 part of Si, 1.58-1.68 parts of Mn, lessthan or equal to 0.015 part of P, less than or equal to 0.005 part of S, 0.02-0.03 part of Nb, 0.008-0.02 parts of Ti, 0.015-0.05 part of Al, 0.15-0.25 part of Ni, 0.10-0.18 part of Cu, 0.10-0.18 partof Cr, less than or equal to 0.42 part of Ceq, and the balance Fe and inevitable impurities. A process comprises the following steps of smelting, heating, rolling, relaxation and cooling. According to the production method, the high-toughness steel plate with the low-temperature impact requirement of more than 40 DEG C is produced by utilizing a continuous casting blank, the maximum thickness canreach 150 mm, the limitation of the traditional TMCP process for rolling extra-thick plate compression ratio by using the continuous casting blank is broken through, the tissue performance of the thick-specification steel plate is improved through tissue regulation and control technology, no additional heat treatment is needed, the process is simple, and the alloy and the production cost are reduced; and the production method can be widely applied to the manufacturing of a plurality of fields such as shipbuilding, maritime work, wind power, bridges, buildings and engineering machinery.

Description

technical field [0001] The invention belongs to the technical field of metal material smelting, and in particular relates to a production method of a low-carbon-equivalent extra-thick steel plate Q460E. Background technique [0002] Extra-thick steel plates generally refer to steel plates with a thickness of more than 60mm. In the known technology, the TMCP process can generally only be used for rolling high-toughness steel plates below 60 mm in size and requiring impact at -40°C. Due to the limitation of the compression ratio, if the extra-thick steel plate is produced by the TMCP process, the original austenite grains will not be fully recrystallized and refined during the rolling process, and the structure is generally coarse and the toughness will deteriorate. Especially for the ultra-thick structural steel plate of the Q460E level, due to the relatively high strength and toughness requirements, the maximum thickness of the existing domestic technology is only 120mm, an...

AI Technical Summary

Problems solved by technology

Due to the limitation of the compression ratio, if the extra-thick steel plate is produced by the TMCP process, the original austenite grains will not be fully recrystallized and refined during the rolling process, the structure is generally coarse, and the toughness will deteriorate

Especially for the ultra-thick structural steel plate of Q460E level, due to the relatively high strength and toughness requirements, the maximum thickness of the existing domestic technology is only 120mm, and the die-casting process is generally used for production. At the same time of high C and high Mn content, a large amount of Cr, Mo, Ni, V and other elements are added to the steel to ensure the strength and toughness of the extra-thick plate by improving the hardenability of the steel plate and adding a quenching and tempering heat treatment process. That is to say, it increases the production cost and energy consumption, and also prolongs the production and delivery cycle. At the same time, the carbon equivalent Ceq of the steel plate is relatively high, which is not conducive to welding

[0003] Chinese patent application number 201510153521.5 discloses "a Q460E steel plate with a thickness exceeding 120mm and its manufacturing method". The content of the invention is to produce extra-thick Q460E steel plates through the DQ+normalizing process. The production process is complicated, the alloy cost is high, and the Ceq is high. Not conducive to subsequent use

Chinese Patent Application No. 201110176678.1 discloses "a high-strength toughness structural steel Q460E thick plate and its production method". The traditional TMCP process is used to produce extra-thick steel plate Q460E, and the recrystallization of austenite in the rough rolling stage and the grain pressure in the finish rolling stage are adopted. The flat elongation method is used to refine the grains. This method cannot get rid of the limitation of the compression ratio. Even if the rolling concept of "high temperature, low speed, and large reduction" is strictly adhered to, it can only produce steel plates below 100mm, and at the same time, Ceq≤0.48 control is too high

Chinese patent application No. 201310329673.7 discloses "Large single weight and extra thick Q460 grade high strength structural steel plate and its manufacturing method". It is also through the traditional rolling method, which cannot get rid of the limitation of the compression ratio. The continuous casting billet with a thickness of 400mm can only produce the largest steel plate. Q460D extra thick product with a thickness of 120mm

Images