STP648

    Estimating the Fatigue Crack Initiation Life of Welds

    Published: Jan 1978


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    Abstract

    The fatigue crack initiation life (cycles to obtain a 0.25-mm fatigue crack) was estimated for butt welds using strain-controlled fatigue concepts. Key developments which facilitated these estimates were the assumption of ??(Kf)max conditions (the largest value of ??Kf possible for a given weld shape), the use of computer simulation methods which modeled cyclic hardening and softening as well as mean stress relaxation effects, and the use of the fatigue properties of the actual weld zone in which the initial notch was located. The initiation life was found to be very sensitive to changes in ??Kf, but rather insensitive to strength level. The importance of residual stresses and mean stress varied with material as did the fraction of total life devoted to crack initiation. Mild steel (ASTM Specification for Structural Steel (A 36)) high strength, low alloy (ASTM Specification for High-Yield Strength, Quenched and Tempered Alloy Steel Plate, Suitable for Welding (A 514)) steel and aluminum alloy welds were considered.

    Keywords:

    fatigue tests, life estimations, weldments, crack initiation, weld defects


    Author Information:

    Lawrence, FV
    Professor, Departments of Civil Engineering and of Metallurgy and Mining Engineering, and research assistant, Department of Metallurgy and Mining Engineering, University of Illinois at Urbana-Champaign, Urbana, Ill

    Burk, JD
    Professor, Departments of Civil Engineering and of Metallurgy and Mining Engineering, and research assistant, Department of Metallurgy and Mining Engineering, University of Illinois at Urbana-Champaign, Urbana, Ill

    Mattos, RJ
    Quality control and research manager, Siderurgica de Medellin, Simesa, Medellin,

    Higashida, Y
    Research engineer, Hiratsuka Research Laboratory, Sumitomo Heavy Industries, Ltd., Tokyo,


    Paper ID: STP33393S

    Committee/Subcommittee: E08.05

    DOI: 10.1520/STP33393S


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