Fatigue Behavior of Resistance Spot Welded High Strength Steel Sheets with Different Nugget Sizes

Abstract

Spot welds are fabricated using high strength and low carbon steel sheets with three different strength levels by a resistance spot welding (RSW) procedure. The nugget sizes are changed by controlling welding process parameters. Subsequently, tensile-shear fatigue tests are conducted to investigate the effects of strength levels of steels and nugget sizes on the fatigue behavior of welds. The fatigue strengths of the welds with 4√t nugget size are nearly the same irrespective of strength levels of steels, because fatigue crack propagation life is dominant in total fatigue life. In the welds with 3√t nugget size, the steel with higher strength exhibits lower joint fatigue strength.