Welding conditions are important factors for performing good welding. In this study, the effects of thermal histories on the strength of weld metal is presumed by experiment and the heat conduc tion analysis by the finite element method. The relation between the thermal history near the fillet weld and the strength of a weld metal is obtained by experiment. And strength of weld metal is presumed from the cooling speed in heat conduction analysis. As a result, it was good correlation that cooling speed near the welding part in heat conduction analysis and ultimate strength in weld metal in the range of this experiment.
