Accession Number : ADA139119

Title :   A Detailed Comparison of Hydrogen and Mercury Embrittlement in Monel 400.

Descriptive Note : Master's thesis,


Personal Author(s) : Fredell,R S

PDF Url : ADA139119

Report Date : Dec 1983

Pagination or Media Count : 96

Abstract : Slow strain rate tensile tests were performed on annealed Monel 400 specimens, with grain sizes ranging from 35 to 500 micrometers, in air, liquid mercury, and gaseous hydrogen. Annealed 250 micrometer grain size Monel 400 samples were also tested, at strain rates ranging from .016/s to .0000016/s, and in high cycle fatigue, in the three environments. The similarities in mechanical behavior and fractographic appearance between hydrogen and mercury embrittlement were then analyzed. The results were compared with the predictions made by some of the current theories of hydrogen and mercury embrittlement. The tests showed that Monel 400 is embrittled by both gaseous hydrogen and liquid mercury, and that the latter is the more severe environment. A common fracture sequence was identified in both environments, and the alloy became more embrittled with the decreasing strain rate. These results pointed to a thermally activated embrittlement mechanism for hydrogen and mercury. The effect of increasing grain size caused mixed results in the tests in mercury, but caused a steady decrease in hydrogen embrittlement. Two competing processes were tentatively identified as the causes of the grain size effect.

Descriptors :   *Nickel alloys, *Copper alloys, *Embrittlement, Test methods, Tensile properties, Strain rate, Annealing, Grain size, Hydrogen embrittlement, Mercury, Fatigue tests(Mechanics), Stresses, Diffusion, Penetration, Air, Liquid metals, Ductility, Fracture(Mechanics), Crack propagation, Fatigue life

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE