This paper deals with low-cycle fatigue life of full-penetration weld joint. The objective is to clarify the influence of the shape and the hardness distribution near the weld toe on low-cycle fatigue life. Cyclic loading was applied to the two types of weld joints which had different shapes and hardness distributions near the weld toe. Low-cycle fatigue life of the weld joint with smooth shape and hard weld metal was superior because of late crack initiation. Digital image correlation (DIC) method also demonstrated that the difference of the hardness distribution caused the different strain distribution and it led to the difference of deformation capacity until crack initiation.
