Sulzer Bros. Ltd., Winterthur,
Pages: 13 Published: Jan 1979
The response of slow strain-rate measurements to heat treatment of a cast, low carbon, martensitic stainless steel in 3 percent sodium chloride solution under cathodic and anodic polarization and Alloy 600 in 0.1 M sulfuric acid solution (poisoned with arsenic) under cathodic polarization has been investigated. The relative reduction of area evaluation was very sensitive to heat treatment and electrochemical polarization effects in both corrosion systems.
The reduction of area measurements on the stainless steel revealed a minimum and a maximum crack sensitivity after tempering at 873 K if the straining electrode were cathodically and anodically polarized, respectively. The test results are explained by hydrogen assisted cracking and active path cracking under cathodic and anodic polarization, respectively.
Alloy 600 samples in poisoned sulfuric acid showed a pronounced decrease in the relative reduction of area after a 50 percent cold deformation plus low temperature aging treatment at 673 K during 500 h. The same metallurgical state had been shown to be especially prone to caustic embrittlement at high temperature. It seems that the slow strain-rate test, as performed in this investigation, can be used as a sensitive method to detect variations in the susceptibility to environmentally induced degradation of Alloy 600 in high temperature caustic solutions.
steel castings, nickel alloys, stress corrosion cracking, hydrogen embrittlement, active path cracking, heat treatment, constant strain rate method, sodium chloride, sulfuric acid
Paper ID: STP38124S