The environmentally assisted cracking or hydrogen embrittlement (HE) of a precipitation-hardening stainfess steel, PH13–8Mo (UNS(1) S13800), has been investigated by simulated real-life testing and accelerated slow strain rate testing (SSRT). The simulated real-life tests involved alternate immersion in 3.5% NaCl of notched specimens galvanically coupled to aluminum, while in the SSRT smooth specimens were galvanostatically charged with hydrogen. In both cases, specimens were tested in an underaged, a peak-aged, and an overaged condition. The findings for both tests show that the susceptibility of the steel to hydrogen embrittlement decreases as the aging temperature is increased. This means that the susceptibility is not dependent solely on strength but must be related to microstructural variations. This is discussed with reference to transmission electron microscopy (TEM) micrographs. In addition to the above tests, elastic slow strain rate tests, in which the specimens are prestrained in air before restraining while charging with hydrogen, were carried out to investigate the role of plastic straining in crack initiation.

Subject
Environmental cracking, Test methods, Materials, Notches, Stress, Mechanical failure, Steel, Stress corrosion cracking, Alternate immersion tests, Aging, Slow strain rate technique, Austenite, Hydrogen
Keywords:
accelerated lab testing, alternate immersion test, elastic slow strain rate test, electron microscope, hydrogen embrittlement, PH13-8Mo steel, precipitation hardening, slow strain rate test
National Association of Corrosion Engineers
1990
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