SEDL / STP / STP1049-EB / STP24083S

Corrosion Fatigue Cracking of Chromium-Containing Steels

Harty, BD
Research officer, University of Cape Town, Cape Town,

Noël, REJ
Engineer, Forges Tardieu Ltd., Port Louis, Mauritius

Pages: 16    Published: Jan 1990

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Abstract

Three chromium-containing steels, 3CR12, Alloy 825, and AISI 431, have been subjected to cyclic loading in air, distilled water, and low chloride containing waters. The 3CR12 steel showed significant fatigue crack growth rate (FCGR) enhancement when subjected to the aqueous environments. Fractography revealed the presence of isolated regions of intergranular and cleavage cracking that were correlated with plateaus observed on the FCGR curves. The Alloy 825 steel showed a FCGR enhancement in the aqueous environments but exhibited a decrease in FCGR with an increase in chloride content. The fracture was observed to be a mixed mode, that is, intergranular separation and transgranular cleavage. The AISI 431 stainless steel exhibited a FCGR enhancement and a low density of widely distributed intergranular features when tested in distilled water; in the chloride-containing environments, the FCGRs decreased progressively with respect to the air data. The corrosion fatigue behavior of the three steels has been discussed in terms of dissolution and hydrogen-assisted cracking.