Solidification Cracking in Low Alloy Steel Weld Metals

  • Edmund J. Morgan-Warren

    Student thesis: Doctoral ThesisDoctor of Philosophy


    A study has been made of the effects of material composition
    and welding variables, particularly speed, on weld metal
    solidification cracking. This has involved low alloy steels
    to specifications En24, SAE4130, ASTM A387B, and several
    aircraft steels. Existing relationships between composition
    and cracking have been critically examined, and an improved
    expression, based on regression analysis, has been developed
    using data relating to some 80 Steels. Practical cracking
    tests were carried out using the Huxley test, and a comparison
    of these results with the predictions of the regression
    analysis confirmed the crack-promoting influences of sulphur,
    phosphorus and carbon, and isolated the important crack inhibiting
    effect of oxygen.

    The influence of welding speed was found to be complex
    and varied with the composition of the steel. In general an
    increase in speed is detrimental at low speeds, but becomes
    beneficial when the speed is raised. This phenomenon is
    explained by a model in which changes of speed are shown to
    cause opposing effects, which interact to give the characteristic

    The morphology of inclusions was also examined, and
    crack susceptibility was found to be associated with sulphide

    The practical significance of the work is also discussed.
    Apart from exposing important new effects, the results
    facilitate the assessment of chemical effects on cracking; and demonstrate the importance of selecting welding variables
    appropriate to the particular materials being used.

    Two different tests have been used in the work for
    specific purposes. The results demonstrate the overwhelming
    importance of selecting a test suitable for the situation
    under examination.
    Date of Award1972
    Original languageEnglish


    • Solidification
    • cracking
    • low alloy steel
    • weld metals

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