Austenitic stainless steel

Abstract

Disclosed is an austenitic stainless steel which comprises the following components: C: 0.04-0.18%, Si: 1.5% or less, Mn: 2.0% or less, Ni: 6-30%, Cr: 15-30%, N: 0.03-0.35%, and sol.Al: 0.03% or less, and which further comprises at least one component selected from 1.0% or less of Nb, 0.5% or less of V and 0.5% or less of Ti, with the remainder being Fe and impurities, wherein the impurities contain the following components: P: 0.04% or less, S: 0.03% or less, Sn: 0.1% or less, As: 0.01% or less, Zn: 0.01% or less, Pb: 0.01% or less and Sb: 0.01% or less, and wherein the following formulae are fulfilled: P1 = S+[(P+Sn) / 2]+[(As+Zn+Pb+Sb) / 5] = 0.06; and 0.2 = Nb+2(V+Ti) = 1.7-10xP1. The austenitic stainless steel has high strength and, when used in a welded part, can exhibit excellent embrittlement crack resistance during being used at a high temperature. The steel is suitable as a material for an instrument that is intended to be used at a high temperature for a long period, such as a boiler for power generation.

Description

Technical field [0001] The present invention relates to an austenitic stainless steel, and in particular to a high-strength austenitic stainless steel that can be used in high-temperature equipment such as boilers for power generation and has excellent resistance to embrittlement and cracking at the welded portion during high-temperature use. The system is stainless heat-resistant steel. Background technique [0002] In recent years, from the viewpoint of reducing the environmental load, the idea of ​​enabling boilers for power generation to be operated under high temperature and high pressure conditions has been promoted throughout the world, and there has been a demand for superheater tubes and reheater tubes. The austenitic heat-resistant steel of the material has more excellent high-temperature strength. [0003] On the basis of this technical background, various austenitic stainless steels have been disclosed. [0004] For example, Patent Document 1 discloses a method of setti...

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Problems solved by technology

[0008] In addition, the above-mentioned austenitic heat-resistant stainless steel is generally used in a high-temperature environment after being assembled by welding, but there is a problem that the welding heat-affected zone (hereinafter referred to as "heat-affected zone") may be damaged after long-term use in a high-temperature environment. HAZ") the problem of cracks

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