溶接継手の高温低サイクル疲労強度評価法の提案

抄録

Evaluation of the fatigue strength of weldments is important, particularly in nuclear components, but no proper evaluation method has been established because of several complicated factors including its geometric and metallographic discontinuities. In this paper, two fundamental evaluation methods of low cycle fatigue strength at elevated temperatures for weldments were proposed and were applied to the life prediction for SUS 316 stainless steel welded joints and 21/4Cr-1Mo steel welded joints. As a result, the life prediction was found possible within the factor of two on life for SUS 316 stainless steel welded joints. But in the case of 21/4Cr-1Mo steel welded joints, post weld heat treatment (PWHT) was found to affect the accuracy of life prediction. Life prediction was impossible within a factor of two on life for 21/4Cr-1Mo steel welded joints without PWHT. This may be caused by the difference in deformation resistance between base metal and weld metal. This study is being continued to establish a simplified fatigue design rule by modification of the presently proposed methods.