"Improved techniques considered were: control of residual stresses@ control of weld geometry@ increasing base metal strength@ and state of the steel sheet surface. This study showed that the fatigue resistance of tensile-shear spot welds (particularly HSLA) could be greatly improved by treatments which either reduced the tensile residual stresses resulting from welding or induced compressive residual stresses at the critical notch-root site of crack initiation and early growth. The improvements possible through modification of weld geometry were smaller than those possible through control of residual stresses except for the improvements resulting from the reduction of joint rotation. A three stage model for predicting the fatigue life of tensile-shear spot welds was developed. Ways of improving the fatigue resistance of electrical resistance spot welds were sought. In this study@ the effects of expulsion@ weld forging@ and surfacing condition on the fatigue behavior of electrical resistance spot welds were researched as well as the behavior of simple adhesive-bonded and weld-bonded lap joints. Weld-forging was found to be beneficial only for the tensile-shear welds. Adhesive bonded joints had the highest fatigue strength for both 2-sheet and 3-sheet joints. Weld-bonded joints generally had a lower fatigue resistance than the adhesive-bonded joint but a much higher fatigue resistance than the as-welded resistance spot weld.The Welding Research Council is publishing this WRC Bulletin covering the results of two studies on ""Improving Steel Spot Weld Fatigue Resistance."" The work was guided by the American Iron and Steel Institute Committee of Sheet Steel Producers Task Force on Fatigue"
BULLETIN 384-1993 history
1993BULLETIN 384-1993 IMPROVING STEEL SPOT WELD FATIGUE RESISTANCE: STUDY I: EFFECT OF TEMPER CYCLE@ MECHANICAL TREATMENTS@ WELD GEOMETRY AND WELDING CONDITIONS ON SHEET STEEL SPOT WELD FATIGUE RESISTANCE ; STUDY II: EFFE