S460ML extra-thick steel plate and production method thereof

Abstract

The invention discloses an S460ML extra-thick steel plate. Low carbon composition design is adopted, low Nb microalloying is added, an appropriate amount of Cr element improves the strength of steel,an appropriate amount of Ni element improves low-temperature impact toughness, the thermomechanical control process (TMCP) rolling technology with a low compression ratio of continuous casting blanksis adopted, rough rolling of a wide and thick plate mill under high pressure, two-stage ultralow temperature control rolling, ultrafast cooling after rolling and other technologies are utilized, the S460ML extra-thick steel plate is developed, the maximum thickness of the steel plate is 120mm, the performance is up to EN10025-4 standard requirements, and the low-temperature impact performance of the steel plate is excellent, especially the low-temperature impact energy at the temperature of -50 DEG C is equal to or higher than 100J. Because the carbon equivalent value (CEV) of the steel plateis equal to or less than 0.39%, the Pcm is equal to or less than 0.18%, the welding performance is more excellent, the economic and mass production of the steel plate can be realized, the use requirements of marine engineering and other complex working conditions and environments are met, and the comprehensive mechanical performance index reaches the same level of countries outside China.

Description

technical field [0001] The invention relates to the technical field of metallurgy, in particular to an extra-thick steel plate and a production process thereof. Background technique [0002] Marine structures need to withstand the test of harsh environments such as typhoon, severe cold and high salt spray on the sea surface. Therefore, steel plates for marine structures are required not only to have high strength and high plasticity, but also to have excellent low-temperature toughness, good welding performance, etc., especially in service. Underwater structural parts such as transition sections need to meet the impact at a lower temperature of -50°C to ensure that steel and equipment can adapt to various loads and low temperature environments, and meet the requirements of various complex working conditions and harsh natural environments at sea. [0003] S460ML is the steel grade with the highest strength level and the most demanding impact requirements specified in the EN10...

AI Technical Summary

Problems solved by technology

[0004] The patent application with application number 201710482286.5 discloses a "thermomechanically rolled extra-thick and easy-to-weld S460M structural steel plate and its production method". The maximum production thickness of the steel plate is only 110mm; the composition design C: 0.06-0.08%, Si: 0.25-0.50 %, Ni: 0.15-0.25%, Nb: 0.060-0.070%, V: 0.040-0.050%, the composition design contains V element, and the Nb content is too high (exceeding standard, EN10025 standard requires Nb≤0.05%), examples The content of Nb+V in the medium is 0.10-0.12%, and the cost of the alloy is high; in addition, the high content of Si is unfavorable to the surface quality of the steel plate, especially the subsequent coating and anti-corrosion requirements will have a certain impact

[0005] The patent application with application number 201810819142.9 discloses "a S460ML thick plate and its preparation method". The maximum production thickness of the steel plate is only 100mm; the composition design C: 0.04-0.06%, Nb: 0.020-0.035%, V: 0.030-0.045% , Ni: 0.10-0.20%, V element is easy to cause the precipitation of aggregated carbides in the grain, reducing the toughness of steel

[0006] The existing low-temperature impact national standard Q460E or European standard S460ML grade steel plate, the normal composition design adopts peritectic steel or relatively low carbon design, high Nb+V and other compound additions, the alloy cost is relatively high; the TMCP process of continuous casting slabs is generally The production thickness does not exceed 110mm, which cannot meet the needs of large-thickness steel plates for marine engineering; thicker steel plates are produced by normalizing heat treatment or quenching and tempering heat treatment, and the steel design costs are high and the production delivery cycle is long