The possible relationship between the hydrogen embrittlement behavior of a cold worked, nickel-cobalt base alloy (MP35N) and impurity effects resulting from heat treatment was examined. Cathodically charged specimens tested in an aqueous H2S containing environment revealed that aging in the temperature range 204 to 593 C (400 to 1100 F) decreased resistance to hydrogen embrittlement. In contrast, heat treating at higher temperatures [697 to 816 C (1250 to 1500 F)] resulted in substantial improvement in the resistance to hydrogen embrittlement while maintaining high strength. Auger analysis of hydrogen embrittled fracture surfaces indicated that this behavior correlated with the concentration of P and S impurities on the major crystallographic boundaries.

Subject
Hydrogen embrittlement, Materials, Nickel based alloys, Fracture surfaces, Mechanical failure, Impurities, Heat, Steel, Elements, Alloys, Heat treatment, Yield strength, Aging
© 1980 National Association of Corrosion Engineers
1980
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