SEDL / STP / STP425-EB / STP46457S

Resistance of Ferritic Stainless Steels to Stress Corrosion Cracking

Bond, A. P.
Research group leader, Climax Molybdenum Company of Michigan, Ann Arbor, Mich.

Marshall, J. D.
research associateassistant metallurgist, Climax Molybdenum Company of MichiganW. S. Tyler Co., Cleveland, Ohio

Dundas, H. J.
Laboratory associate, Climax Molybdenum Company of Michigan, Ann Arbor, Mich.

Pages: 11    Published: Jan 1967

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Abstract

Stress corrosion cracking tests were carried out on 0.020-in.-diameter wires under dead-weight loading in boiling solutions of MgCl², Ca(NO³)², and NaOH. The T430 and T434 ferritic stainless steels were immune to stress corrosion cracking in MgCl² under conditions which caused various austenitic grades to fail in 6 to 46 min. Pitting corrosion in MgCl² reduced the cross-sectional area of the ferritic steel specimens to the extent that they could not support the load, and they failed in a ductile manner. Stressed specimens of ferritic stainless steels did not fracture in Ca(NO³)² or NaOH even after heat treatments which led to intergranular corrosion. Corrosion potential measurements were made on the stressed specimens and correlated with various stages in the stress-corrosion cracking process.