抄録
The spot weld of high tensile steel does not improve as base metal strength. However, with the application of high tensile steel by the body light weighting, the strength evaluation of the spot weld becomes important in a design. The previous studies show that a index to estimate fatigue strength and a possibility to improve fatigue strength. This study achieve extensive improvement of the fatigue strength by compressive residual stress that can apply to 590〜1500MPa grade steel. This improvement correspond to the estimation from the fatigue limit diagram of notched specimen.
