High tempering parameter SR embrittlement resistant cryogenic nickel steel and manufacture method thereof

Abstract

A high tempering parameter SR embrittlement resistant cryogenic nickel steel and a manufacture method thereof. The nickel steel comprises, by weight, 0.025%-0.060% of C, Si no more than 0.15%, 0.45%-0.85% of Mn, P no more than 0.012%, S no more than 0.0020%, 0.10%-0.40% of Cu, 2.80%-3.80% of Ni, 0.10%-0.30% of Cr, 0.05%-0.30% of Mo, 0.040%-0.070% of Als, 0.006%-0.012% of Ti, 0.008%-0.025% of Nb, N no more than 0.0040%, 0.001%-0.003% of Ca, residual iron and unavoidable inclusions. According to optimized controlled rolling and a normalizing plus tempering technology, the nickel steel gains extremely high ultralow temperature toughness, excellent HIC / SCC resistance, weldability and bearing capacity of high heat input welding; besides, the nickel steel has excellent high tempering parameter SR embrittlement resistance characteristic, and is especially suitable for manufacture of large-scale LPG low temperature storage tank, low temperature storage tank for ship and large-scale steel structure for ice ocean and polar region.

Description

technical field [0001] The present invention relates to low-temperature steel and its manufacturing method, in particular to low-temperature nickel steel resistant to high tempering parameter SR embrittlement and its manufacturing method. Low-temperature nickel steel that is welded and resistant to HIC and SCC is mainly used for the manufacture of LPG low-temperature storage tanks and marine low-temperature storage tanks. 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 containers, building structures, automobile industry, railway transportation and machinery manufacturing among. The properties of low-carbon (high-strength) low-alloy steel depend on its chemical composition and the process system of the manufacturing process, among which strength, toughness and weldability are...

AI Technical Summary

Problems solved by technology

[0005] However, due to the two times of normalizing heat treatment, the manufacturing cycle of the steel plate is long and the manufacturing cost is high. More importantly, when the thickness of the steel plate exceeds 60mm, the impact toughness at -101°C of the steel plate after high tempering parameter SR is unstable and fluctuates greatly. , and the strength declines greatly, and the quality control of the steel plate is poor ("Study on the brittleness of steel の烧どし brittleness niguan する", 1976, P123~P144, Japan Iron and Steel Association; ibid, P95~P105, Japan Iron and Steel Association; "Iron and Steel", S281, 1977; "Iron and Steel", S326, 1978)

[0006] In addition, when welding with large input energy, the low-temperature toughness of the welding heat-affected zone (HAZ) is seriously deteriorated, and the low-temperature ductile-brittle transition temperature of the heat-affected zone (HAZ) is generally difficult to reach -80°C, let alone reach ultra-low temperature- 101°C (such as European Patent EP 0288054A2, EP0839921A1, US Patent 4851052)

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