Ni-series low-temperature steel, manufacture method thereof, liquefied natural gas storage tank and ship body for transportation ship

Abstract

The invention provides Ni-series low-temperature steel, a manufacture method thereof, a liquefied natural gas storage tank and a ship body for a transportation ship. The Ni-series low-temperature steel includes the following chemical compositions by mass percentage: 0.02-0.10% of C, 0.01-0.20% of Si, 0.50-0.75% of Mn, less than or equal to 0.010% of P, less than or equal to 0.004% of S, 8.50-9.50% of Ni, 0.005-0.40% of Al, 0.005-0.40% of Ti, 0.0005-0.003% of O, 0.0010-0.01% of N, 0.0005-0.004% of Ca, 0.001-1.50% of Cu, 0.001-0.16% of Mo and the balance being Fe. The manufacture method includes steps of: adopting a basic oxygen furnace (BOF)(or an electric arc furnace(EAF)) for smelting+ low frequency (LF)+ VD(or RH) refining technology for refining; adopting a secondary cold area weak cold+ stable low casting process to be matched for steel continuous casting; adopting low-temperature heating+ controlled rolling technology for steel rolling and directly quenching at the temperature above Ar3; and adopting the critical hardening+ tempering process for thermal treatment of steel. Through experiments of low-temperature impacting, non destructive testing (NDT), dark trace (DT), crack tip opening displacement (CTOD), K1a and the like, the Ni-series low-temperature steel is proved to have the advantages of having good obdurability matching and suitable for manufacturing ultra-large type liquefied natural gas (LNG) storage tanks, wherein manufacture volume of the LNG storage tanks exceeds 2*105m<3>, maximum wall thickness exceeds 50mm, and the LNG storage tanks are ultra-high in requirements for safety.

Description

technical field [0001] The invention relates to Ni-based low-temperature steel, a method for manufacturing the Ni-based low-temperature steel, and a liquefied natural gas storage tank and a hull for a liquefied natural gas transport ship manufactured by using the Ni-based low-temperature steel. Background technique [0002] As of 2010, China has become one of the largest users of liquefied natural gas (LNG) in the world. It is estimated that 10-15 3 million-ton LNG storage and transportation stations will be built along the coast in 2015, and gradually expanded to 5-10 million tons. At the same time, there will be a considerable amount of planning for small satellite storage and transportation stations, peak shaving stations, and LNG carriers. However, according to a report released by the "China-US Oil and Natural Gas Forum" in June 2005, there are as many as 43 LNG storage and transportation stations under construction and planned in North America; the surge in global dema...

AI Technical Summary

Problems solved by technology

In short, from the 1940s to the present, foreign countries have not interrupted the research and development of 9% Ni steel.

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