Austenitic stainless steel with excellent ultra-low temperature performance and manufacturing method thereof

Abstract

Provided are austenitic stainless steel with excellent ultra-low temperature performance and a manufacturing method thereof. Chemical composition weight percentage of the austenitic stainless steel isC <= 0.03%, Si 0.2 to 1.0%, and Mn 0.2 to 1. 0%, Cr 20.0 to 21.8%, Ni 11.5 to 12.8%, N 0.10 to 0.15%, Cu 0.5 to 1.5%, Mo <= 0.3%, P <= 0.04%, S <= 0.02%, the rest are Fe and inevitable impurities, Fn<51, and Fn=10Cr%+14Si+12Mo%-10Ni%-200N%-250C%-8Cu%-5Mn%. The ferrite content in the structure is < 0.5%. magnetic permeability of the austenitic stainless steel is < 1.01, fracture toughness propertyof 7K is > 200MPa.m1/2, and 7K yield strength is > 750MPa. The austenitic stainless steel can be used for nuclear power and superconducting and other industries which have special requirements on ultra-low temperature toughness and ultra-low temperature strength.

Description

technical field [0001] The invention belongs to the field of austenitic stainless steel, and in particular relates to an austenitic stainless steel with excellent ultra-low temperature performance and a manufacturing method thereof. Background technique [0002] Austenitic stainless steel hard materials have excellent low-temperature toughness, and the impact energy at -100°C is usually greater than 60J. Therefore, they are widely used in industries such as low-temperature storage tanks such as LNG. However, in some industries, such as the superconducting industry, the temperature of the material is close to absolute zero, and there is a strong electromagnetic field, and the performance of conventional materials cannot meet the requirements. [0003] At present, the widely used austenitic stainless steels are 304 and 316. According to the ASTM A240 standard, the standard composition of 304 is: C≤0.08%, Si≤0.75%, Mn≤2.0%, Cr 17.5~19.5%, Ni 8.0~10.5%, generally, the typical c...

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Problems solved by technology

[0008] It can be seen from the above patents that the current austenitic stainless steel for ultra-low temperature all takes into account the influence of ferrite content on low temperature toughness, and controls the ferrite content by controlling the nickel equivalent and chromium equivalent. However, its impact on the ferrite content The control is not accurate enough, and the ferrite content is still high. At the same time, for stainless steel used near absolute zero, other characteristics of the material need to be further considered, such as improving toughness, controlling carbides, nitrides, and intermetallic phases. Precipitation, and increased strength at ultra-low temperatures

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