Ultrahigh-strength maritime steel plate with yield strength of 960MPa and manufacturing method thereof

Abstract

The invention discloses an ultrahigh-strength maritime steel plate with the yield strength of 960MPa and a manufacturing method thereof. Steel comprises, 0.07%-0.15% of C, 0.02%-0.15% of Si, 0.80%-1.30% of Mn, no more than 0.010% of P, no more than 0.003% of S, 0.35%-0.80% of Cr, 1.00%-2.00% of Ni, 0.40%-0.70% of Mo, 0.20%-0.50% of Cu, 0.01%-0.03% of Nb, 0.03%-0.06% of V, no more than 0.014% of Ti, 0.03%-0.07% of Als, 0.0007%-0.0015% of B, and the balance Fe and inevitable impurities. The soaking temperature of a plate blank is 1130-1180 DEG C, the initial rolling temperature in the first stage is 1050-1150 DEG C, the initial rolling temperature in the second stage is equal to or less than 900 DEG C, the final rolling temperature is equal to or higher than 810 DEG C, the plate blank is placed in a slow cooling tank to be slowly cooled after being rolled, the slow cooling temperature is not lower than 350 DEG, and the slow cooling time is not less than 24h; and then, quenching and tempering is conducted, the thickness of the steel plate is 8-50mm, and the tenacity of the steel plate at the low temperature -40DEG C is good.

Description

technical field [0001] The invention belongs to the field of iron and steel material preparation, and in particular relates to a 960MPa grade marine steel plate with excellent low-temperature impact toughness and a manufacturing method thereof. Background technique [0002] In recent years, with people's continuous exploration and development of the marine field, the steel required for supporting ships and marine engineering and its research and development and production have become the top priority. The emphasis on the safety of the platform’s ultra-deep water operations and the lightweight requirements of marine engineering equipment have continuously increased the strength of steel used in marine engineering equipment. It is necessary to design a lighter and thinner force-bearing structure, thereby reducing the platform’s center of gravity, improving stability, and reducing welding. At the same time, it increases the payload of important equipment and improves equipment ...

AI Technical Summary

Problems solved by technology

[0003] At present, steel plates with a yield strength of 960MPa designed and produced at home and abroad are generally poor in low-temperature impact toughness, which cannot meet the requirements of marine engineering equipment.

In addition, the TMCP or TMCP+T process is used to produce very high-strength steel plates with a yield strength of 960 MPa, which has extremely high requirements on the capabilities of rolling mills and straightening equipment, and it is difficult to guarantee the uniformity of plate shape and steel plate performance.

[0004] The invention patent of application number 200510024775.3 "Ultra-high-strength steel plate with yield strength above 960MPa and its manufacturing method" adopts TMCP / TMCP+tempering process to produce steel plate with yield strength of 960MPa. The disadvantage of this patent is that it is limited by steel composition and production conditions. The thickness of the finished plate is ≤16mm, and its low-temperature impact toughness is not high, and the impact energy of the actual product at -40°C is only 33-50J

No matter in terms of composition range or delivery status, it cannot meet the index requirements of 960MPa grade marine steel

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