Large-thickness and high-strength steel plate applicable to low temperature and manufacturing method thereof

Abstract

The invention discloses a large-thickness and high-strength steel plate applicable to low temperature. The steel plate comprises the following chemical components in percentage by mass: 0.08-0.15% of C, 0.15-0.35% of Si, 0.95-1.25% of Mn, smaller than or equal to 0.01% of P, smaller than or equal to 0.005% of S, 0.35-0.55% of Cr, 0.35-0.55% of Mo, 0.88-1.5% of Ni, 0.20-0.40% of Cu, 0.02-0.08% of Al, 0.03-0.05% of V, 0.02-0.04% of Nb, smaller than or equal to 0.02% of Ti, smaller than or equal to 0.006% of N, 0.0008-0.002% of B and the balance of Fe and inevitable impurity elements. The manufacturing method of the steel plate adopts the following process flows: smelting and continuously casting, slowly cooling by covering, clearing at a certain temperature, heating, rolling, performing air cooling and straightening, slowly cooling, and quenching and tempering. The manufactured steel plate has the thickness of 80-125mm, has high strength, good ductility and high low-temperature toughness, can be adapted to a minus 60 DEG C low-temperature environment, can meet a requirement on high Z-direction performance, and has excellent overall performance.

Description

technical field [0001] The invention belongs to the field of large-thickness, high-strength steel plate manufacturing, and specifically relates to a steel plate with a yield strength of 550 MPa and a thickness of 80-125 mm and a manufacturing method thereof. Tear performance ≥ 35%. Background technique [0002] The depletion of land and shallow sea oil and gas resources makes the exploitation of offshore oil and gas resources gradually develop in deep waters. Deep-water oil and gas drilling requires large-scale, lightweight, long-life, and mobile offshore engineering equipment, which requires that the steel plates used in the manufacture of marine engineering equipment should have high strength, high toughness, and large thickness to meet the requirements of waves and tides. These large-scale equipment can work in a long-term, safe, reliable and stable manner in severe deep-water marine environments such as storms, storms and cold drift ice. Since marine engineering equipm...

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Problems solved by technology

[0006] The invention patent of patent publication number CN103540850A can manufacture steel plates with a maximum thickness of 80mm, but it can only meet the requirements of impact toughness at -20°C; the invention application of patent publication number CN102691000A can manufacture steel plates with a maximum thickness of 100mm, but its impact toughness Can only meet the use requirements at -40°C

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