STP522

    Influence of Nitrogen on the Creep-Rupture Properties of Type 316 Steel

    Published: Jan 1973


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    Abstract

    An experimental program has been conducted to determine the influence of nitrogen on the creep and rupture properties of Type 316 stainless steel. A series of commercial and laboratory heats with similar base composition but varying nitrogen contents were utilized in the study. The nitrogen content of the heats ranged from 0.039 to 0.15 percent.

    The creep and rupture strengths of the steel at 1200 F increased with increasing nitrogen level. The stress for rupture in 1000 and 10 000 h was approximately 40 percent higher for the 0.15 percent nitrogen heat than for the 0.039 percent nitrogen alloy. The stress to produce a minimum creep rate of 0.01 percent per 1000 h increased by 50 percent over the same nitrogen range.

    A ferrite containing heat was also tested in the program. Ferrite was shown to decrease creep resistance and increase rupture ductility. No significant influence of this phase was noted with respect to rupture strength.

    Various parameter extrapolation methods were compared in their ability to predict the location of a break in the rupture curve of one of the nitrogen containing heats. Long time rupture tests were conducted to pinpoint the exact position of this change in slope.

    Keywords:

    nitrogen, creep strength, austenitic stainless steels, creep rupture strength, ferrite, microstructure, extrapolations, creep rate


    Author Information:

    Cullen, TM
    Section manager and supervisor, Combustion Engineering, Inc., Chattanooga, Tenn.

    Davis, MW
    Section manager and supervisor, Combustion Engineering, Inc., Chattanooga, Tenn.


    Paper ID: STP36503S

    Committee/Subcommittee: A01.13

    DOI: 10.1520/STP36503S


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