Abstract
Effect of local heat treatment on residual stresses of 13 Cr cast steel (SCS5) is investigated by an experimental analysis of the transient thermal stresses of weld. The transient thermal stresses are obtained by using both-ends-fixed bar subjected to double thermal cycles simulating welding and local heat treatment. The experimental results are compared with the longitudinal residual stress distributions of butt welded joints which are subjected to local heat treatment. The residual stresses at welds after local heat treatment of which temperature ranges from 500°C to Ac1 transformation point become tensile stresses not less than 400 MPa. Vickers hardness decreases with increase in holding time and rise in holding temperature. It is considered that the variation of residual stresses are mainly attributed to relaxation of thermal stress and reduction in yield stress. From these results one dimensional analysis method is proposed to evaluate residual stresses under local heat treatment. This analysis shows good agreement with the experimental results.
