High tempering parameter PWHT embrittlement resistant, extra thick cryogenic steel plate and manufacture method thereof

Abstract

A high tempering parameter PWHT embrittlement resistant, extra thick cryogenic steel plate and a manufacture method thereof. The steel plate comprises, by weight, 0.030%-0.070% of C, Si no more than 0.15%, 1.30%-1.60% of Mn, P no more than 0.013%, S no more than 0.0025%, 0.040%-0.070% of Als, 0.10%-0.40% of Cu, 0.25-0.65% of Ni, 0.10%-0.30% of Cr, 0.05%-0.25% of Mo, 0.007%-0.013% of Ti, 0.010%-0.030% of Nb, 0.020%-0.050% of V, N no more than 0.0045%, 0.001%-0.004% of Ca, residual iron and unavoidable inclusions. According to optimized controlled rolling and two times of normalizing technology, the steel plate gains extremely high ultralow temperature toughness, excellent HIC / SCC resistance, weldability and bearing capacity of high heat input welding; and more importantly, the steel plate has excellent high tempering parameter PWHT embrittlement resistance characteristic, and is especially suitable for manufacture of large-scale LPG low temperature storage tank, low temperature storage tank for ship and ocean platform for ice ocean.

Description

technical field [0001] The invention relates to a steel plate for low temperature use and a manufacturing method thereof, in particular to an extra-thick steel plate for low temperature use resistant to high tempering parameter PWHT embrittlement and a manufacturing method thereof. Energy-welded and HIC- and SCC-resistant low-temperature 50-kilogram extra-thick steel plates (≥50mm), mainly used for LPG low-temperature storage tanks, marine low-temperature storage tanks, and offshore platforms in ice sea areas. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridge structures, boiler pressure vessels, building structures, automobile industry, railway transportation and machinery under manufacture. The properties of low-carbon (high-strength) low-alloy steel depend on its chemical composition and the pr...

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Problems solved by technology

[0005] Chinese Patent Application No. 200810035029.8 discloses "a low-temperature steel and its manufacturing method". Although it successfully solves the above-mentioned problems, the steel plate of this invention does not involve the research on the law of performance degradation of the steel plate by post-weld heat treatment, and the steel plate is resistant to high tempering parameters. The embrittlement ability of PWHT is poor, after TP≥18.5×10 3 Under the simulated post-weld heat treatment conditions, the single values ​​of impact energy at -80°C of the steel plate are all lower than 80J, which cannot meet the requirements of large-scale low-temperature storage tanks (after the welding of large-scale low-temperature storage tanks is completed, overall heat treatment is required to eliminate the residual stress of welded joints , stabilize and soften the microstructure of welded joints, and improve the safety and reliability of storage tanks during service)

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