Highly corrosion-resistant austenite stainless steel well-suited to brazing

Abstract

The present invention provides austenitic stainless steel which is not only excellent in brazeability, but is also excellent in corrosion resistance in an environment where condensation of combustion exhaust gas causes formation of condensed water which contains nitric acid ions or sulfuric acid ions and which is low in pH or in an environment of an aqueous solution which contains chloride ions, which contains, by mass %, C: 0.080% or less, Si: 1.2 to 3.0%, Mn: 0.4 to 2.0%, P: 0.03% or less, S: 0.003% or less, Ni: 6.0 to 12.0%, Cr: 16.0 to 20.0%, Cu: 0.2 to 3.0%, Al: 0.002 to 0.10%, N: 0.030 to 0.150%, and Mo: 0.1 to 1.0%, has a balance of Fe and unavoidable impurities, and satisfies Formula (A): 1.6@[Cu]×[Si@]4.4 and Formula (B): 0.16@2[N]+[Mo@]1.0.

Description

technical field [0001] The present invention relates to austenitic stainless steel used in structures joined by brazing filler metals such as nickel brazing filler metal and copper brazing filler metal. In particular, the present invention relates to an austenitic stainless steel having excellent brazability and corrosion resistance in an environment where condensed water containing nitrate ions and sulfate ions is generated by condensation of combustion exhaust gas and has a low pH , and excellent corrosion resistance in an aqueous solution environment containing chloride ions. Background technique [0002] Brazing joining is a technique of joining materials by using brazing filler metal having a melting point lower than that of structural materials, and performing heat treatment at a temperature slightly higher than the melting point of the brazing filler metal. Brazing joining is a joining method widely used also in stainless steel. The brazing filler metal used in the ...

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Problems solved by technology

However, the steel sheet proposed in Patent Document 5 is suitable for automobile fuel system components, and although stress corrosion cracking resistance has been studied, there is no description about brazability.

[0013] In addition, when used in exhaust system components of automobiles or secondary heat exchangers of hot water supply equipment equipped with latent heat recoverers, chlorides are contained in the inhaled atmosphere, so especially in high-salt areas near the coast When used in hazardous areas, corrosion resistance in environments containing chloride ions also becomes a problem

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