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Subject: Stress corrosion cracking

Stress corrosion cracking

From: Pat Gallagher <drrust>
Date: Wednesday, May 6, 1998
Jim Moss <clkmkr [at] tiac__net> writes

>... I have
>tried for several months to locate the document that backs up the
>anecdotal story about the gun cartridges being stored in a shed and
>developing Stress Corrosion Cracking as a result of an infestation
>of rats. Can anyone help me locate this document?

Perhaps the references given in the paragraph  below will take you
closer to the original story.

    From U. R. Evans, The Corrosion and Oxidation of Metals:
    Scientific Principles and Practical Applications, Arnold,
    London, 1960, p. 691

    Season Cracking of Brass. Many years ago, much trouble was
    caused by the cracking of brass cartridge cases stored in
    eastern [read Asian] cities  where the air was hot and contained
    ammonia. This was traced down to internal stresses left after
    fabrication, which were largely tensional in the surface layers
    of the parts affected, although balanced by compressional
    stresses in the central zone. The chemical action on the
    intergranular material allowed the grains, initially in tension,
    to contract, leaving definite fissures between one and another.
    The trouble was met with on other highly worked brass articles
    besides cartridge cases and processes were worked out for
    minimizing susceptibility to cracking by annealing; by careful
    choice of time and temperature, the stresses could often be
    dispelled without loss of the highly desirable work-hardness.
    The recommended procedure varies between different types of
    brass, and is laid down in the classical papers of  H. Moore and
    S. Beckinsale, with C. E. Mallinson, J. Inst. Met. 1920, 23,
    225; 1921, 25, 35; 1922, 27, 149; 1923, 29, 285.

Patrick Gallagher

                  Conservation DistList Instance 11:92
                  Distributed: Thursday, May 14, 1998
                       Message Id: cdl-11-92-003
Received on Wednesday, 6 May, 1998

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