STP610: Effects of Composition on Stress-Corrosion Cracking Resistance of Ultrahigh-Strength Steels

    Waid, GM
    Research metallurgist and section chief, Research Center, Republic Steel Corporation, Cleveland, Ohio

    Ault, RT
    Research metallurgist and section chief, Research Center, Republic Steel Corporation, Cleveland, Ohio

    Pages: 14    Published: Jan 1976


    Abstract

    An investigation was made to evaluate the effects of various alloying and impurity elements on the stress-corrosion cracking (SCC) resistance of ultrahigh-strength steels. The influence of phosphorus and sulfur on the SCC threshold parameter, KIscc, of HP 9-4-45 steel heat treated to both bainitic and martensitic microstructures was measured. The bainitic microstructure was consistently more resistant to SCC than was the martensitic structure, and neither phosphorus nor sulfur had a pronounced effect on the KIscc value. However, impurities, especially sulfur, had an adverse effect on fracture toughness. A systematic examination of silicon, chromium, and molybdenum compositional effects on the SCC behavior of 0.40C low-alloy martensitic steels also was included in this study. SCC as measured by the KIscc parameter of these low-alloy steels heat treated to strength levels in the neighborhood of 300 000 psi was, essentially, independent of composition; however, increasing amounts of silicon and possibly chromium decreased the crack-growth rates. The fracture-toughness levels of these alloy steels, however, were highly dependent on compositional variations.

    Keywords:

    stress corrosion, crack propagation, toughness, fracture strength, microstructure, compositions, ultrahigh strength steels


    Paper ID: STP28680S

    Committee/Subcommittee: G01.06

    DOI: 10.1520/STP28680S


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