Ultralow temperature nickel steel with low cost and manufacturing method thereof

Abstract

An ultralow temperature nickel steel with low cost and a manufacturing method thereof. The steel comprises the following components by weight: 0.04-0.070% of C, no more than 0.15% of Si, 0.80-1.20% of Mn, no more than 0.010% of P, 0.0020% of S, 5.00-7.00% of Ni, 0.05-0.25% of Mo, 0.010-0.030% of Als, 0.008-0.018% of Ti, no more than 0.0040% of N, 0.001-0.004% of Ca, and the balance of Fe and the inevitable inclusion. The invention uses a component system containing ultra low C, ultra low Si, middle Mn, low N and ultramicro Ti for treatment of low alloy steel, and controls the value of (%Mn)*[7.33 (%Si) + 5.16 (%Al)] at no more than 1.0, and the value of austenite stabilization index Au / intercritical quenching temperature T at no less than 0.007 and no more than 0.009; an optimized recrystallization controlled rolling and subsequent special heat treatment process endows the ultralow temperature nickel steel with ultrahigh ultralow temperature toughness, excellent weldability and bearing of high heat input welding, and the ultralow temperature nickel steel gains excellent anti-high tempering parameter SR embrittlement characteristics, and can be manufactured at a low cost.

Description

technical field [0001] The invention relates to low-carbon (high-strength) low-alloy steel, in particular to low-cost ultra-low temperature nickel steel and its manufacturing method. Z direction performance ≥ 35%, mainly used for liquefied natural gas storage tanks and marine liquefied natural gas 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 the most important properties of low-carbon (high-strength) low-alloy steel, which are ultimately determined by...

AI Technical Summary

Problems solved by technology

[0007] A large number of existing patent documents only explain how to realize the low-temperature toughness of the base metal steel plate at -40°C to -60°C, and explain less about how to obtain excellent low-temperature toughness in the heat-affected zone (HAZ) under welding conditions. How to ensure low temperature toughness at -196°C in the heat-affected zone (HAZ) of ultra-low temperature nickel steel during input welding

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