High nickel steel for ultralow-temperature pressure vessel and manufacturing method thereof

Abstract

The invention discloses high nickel steel for an ultralow-temperature pressure vessel and a manufacturing method thereof. The high nickel steel comprises the following chemical components, by weight, 0.01-0.08% of C, Si being less than or equal to 0.05%, 0.90-1.20% of Mn, 7.00-7.50% of Ni, 0.05-0.10% of Mo, 0.30-0.60% of Cr, 0.01-0.03% of Ti, S being less than or equal to 0.005%, P being less than or equal to 0.008% and the balance Fe and impurities. Two-stage controlled rolling is adopted. First-stage rolling temperature is greater than or equal to 1050 DEG C, secondary-stage rolling temperature is greater than or equal to 850 DEG C, finish rolling temperature is 750+ / -20 DEG C, and air cooling is carried out after rolling; thermal insulation is carried out for 2min / mm at 800-850 DEG C and quenching is carried out, thermal insulation is carried out for 2min / mm at 630-700 DEG C and quenching is carried out, thermal insulation is carried out for 4min / mm at 550-600 DEG C and tempering is carried out, and air cooling is finally carried out. The high nickel steel for an ultralow-temperature pressure vessel can replace 9% Ni steel. Thus, manufacturing cost of steel for an LNG storage tank is reduced, and direct economic benefit can be created.

Description

technical field [0001] The invention belongs to the field of high-alloy steel manufacturing, and in particular relates to a high-nickel steel for ultra-low temperature pressure vessels suitable for liquefied natural gas (LNG) storage tanks and a manufacturing method thereof. Background technique [0002] With the increasing use of natural gas worldwide, the demand for 9% Ni steel for the construction of liquefied natural gas (LNG) storage tanks is also increasing rapidly. The cost of 9%Ni steel remains high due to its Ni content of 9%, and its products are difficult to push into the market. The report on 7%Ni steel is only available in Volume 28 of the "Proceedings of the Welding Society" published in Japan in 2010 "Development of 7%Ni-TMCP Steel Plate for LNG Storage tanks" in No. 1. Its chemical composition is calculated by weight percentage: C: 0.05%, Si: 0.05%, Mn: 0.80%, Ni: 7.10%, Cr: 0.41%, Mo: 0.04%. In the article, the author did not give the composition range of ...

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Problems solved by technology

The author proposes that the final rolling temperature of 7% Ni steel controlled rolling should be strictly controlled around Ar3, that is, around 650°C, which increases the load on the rolling mill and increases the difficulty of rolling, and the author did not give a specific control Rolling process, and from the aspect of improving the strength and toughness of steel, the content of Mn and Mo is low

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