STP1058

    Fatigue Crack Initiation and Growth in Tensile-Shear Spot Weldments

    Published: Jan 1990


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    Abstract

    Fatigue crack initiation and growth in SAE 960X steel tensile-shear spot welds were studied by sectioning companion specimens and by replicating the exposed site of crack initiation in a presectioned weldment. Constant-amplitude R = 0 and R = -1 tests, as well as variable-load history tests were performed on as-welded weldments and weldments peened (“coined”) after welding.

    Approximately 50% of the total fatigue life was devoted to developing a 0.25-mm-depth crack under constant-amplitude loading in the life range 104 to 106 cycles. At lives greater than 106 cycles, this percentage appeared to increase. Similar results were found under a variable load history, although, in this case, only 40% of the life was devoted to developing a 0.25-mm-depth crack. Postweld coining increased the fatigue life by over an order of magnitude. Several analytical models for predicting the fatigue life of the tensile-shear spot weldments studied were compared.

    Keywords:

    weldments, tensile-shear spot welds, fatigue, fatigue crack initiation, fatigue crack propagation, fatigue life prediction models, high-strength, low alloy (HSLA) spot welds


    Author Information:

    McMahon, JC
    Engineer, Advanced Cardiovascular Systems, Temecula, CA

    Smith, GA
    Engineer, General Electric Corp., Cincinnati, OH

    Lawrence, FV
    Professor of civil engineering and metallurgy, University of Illinois at Urbana, Urbana, IL


    Paper ID: STP24090S

    Committee/Subcommittee: E08.93

    DOI: 10.1520/STP24090S


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