The effects of residual stress on fatigue strength at aweld toe in a multi-pass fillet weld joint were evaluated. Theresidual stresses in the weld joints were varied by controlling thesequence of welding passes. The residual stress at the weld toe was80MPa in the specimen whose last welding pass was on the mainplate side, but it was 170MPa in the specimen whose last pass wason the attachment side. The fatigue strength was nearly the same athigh stress amplitude for both specimens, but the fatigue strengthof the specimen whose last weld pass was on the attachment side.The fatigue strength was nearly the same at high stress amplitudefor both specimens, but the fatigue strength of the specimen whoselast weld pass on the main plate was higher than that of the otherspecimen at low stress amplitude. This difference is due to themagnitude of the initial residual stress and the relaxation of theresidual stress under fatigue cycling. The effects of the residualstress were shown in a modified Goodman diagram, in whichresidual stress is treated as a mean stress.
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