STP108

    Hydrogenizing Effect of Steam on Ferrous Alloys at Elevated Temperatures

    Published: Jan 1951


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    Abstract

    Several grades of stainless steel representative of alloys hardenable by the martensite reaction are heat treated in contrasting atmospheres of (a) steam and (b) carefully dried helium or air to demonstrate the severe damage to the ductility of the steel caused by hydrogen derived from the high-temperature metal-steam reaction. The damage is measured in terms of bendability of 1/4-in. round bar stock, using a specially designed bend test. The results substantiate the theory of the “hydrogen potential” of metal-steam reactions advanced by the senior author several years ago and suggest that an important extent of damage is being currently born by metallurgical applications where steam conditions are present and the hydrogenizing effect is not recognized. Hardened steels which endure a full bend after quenching from a dry atmosphere fail at a relatively low angle if steam is admitted into the heat treating furnace. This is specifically true of type 410 (or 403) stainless steel, which is designed for service in steam turbines. Furthermore, the effect of steam is extremely rapid, an exposure for one minute at the close of a heat treatment in dry helium causing virtually as much injury as a complete steam treatment. Recovery of the embrittled steel is studied, and an “aging minimum” is found similar to that observed in recovery from pickling brittleness.


    Author Information:

    Zapffe, C. A.
    Consulting Metallurgists, Baltimore, Md.

    Landgraf, F. K.
    Consulting Metallurgists, Baltimore, Md.


    Paper ID: STP46732S

    Committee/Subcommittee: G01.04

    DOI: 10.1520/STP46732S


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