STP665: The Role of Film Rupture During Slow Strain-Rate Stress Corrosion Cracking Testing

    Diegle, RB
    Senior research metallurgist and senior research leader, Battelle Columbus Laboratories, Columbus, Ohio

    Boyd, WK
    Senior research metallurgist and senior research leader, Battelle Columbus Laboratories, Columbus, Ohio

    Pages: 21    Published: Jan 1979


    Abstract

    The unique nature of the slow strain-rate technique for stress corrosion testing is discussed in terms of its ability to maintain repetitive rupture of corrosion films. It is first shown that the surfaces of alloys of engineering importance tend to be covered with films under electrochemical conditions that promote stress corrosion cracking (SCC). The relevance of this observation to conditions prevailing directly at the stress corrosion crack tip is considered next, and it is shown that a film-covered tip is a likely probability in several alloy-corrodent systems. It is proposed that film rupture can be considered a prerequisite for the operation of the two major proposed SCC mechanisms, namely, anodic dissolution and hydrogen embrittlement. The predominance of intergranular or transgranular cracking is ascribed to the morphology of slip within the alloys and possibly to the effect of solute segregation on corrosion kinetics. It is concluded that the success of the slow strain-rate technique as a severe test of SCC susceptibility results from its ability to expose the crack tip region to the aggressive environment through film rupture.

    Keywords:

    corrosion prevention, stress corrosion cracking, corrosion, cracks, hydrogen embrittlement, intergranular corrosion, transgranular corrosion


    Paper ID: STP38107S

    Committee/Subcommittee: G01.06

    DOI: 10.1520/STP38107S


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