水素脆化と熱ひずみぜい化の複合効果を考慮した溶接低温割れの検討

抄録

Toe crack and/or weld metal crack often occurred in double side welded joint. It has been appeared in previous work that the factors causing these cracks had been due to both effects of hot strain caused by angular distortion at blue embrittlement temperature range and diffusible hydrogen from 2nd side weld.
In this study, to investigate the effect fo hot strain on cold crack sensitivity of toe and weld metal, using 14 commercial steels and weld metals, notch tensile strength was measured for hydrogen charged synthetic heat cycle specimen pre-strained at blue embrittlement temperature range. And local strain for fracture was evaluated, converting the notch tensile strength into local strain by Neuber's method. Furthermore, considering both results of above tests, a formula to estimate the critical preheat-interpass temperature in multipass welding using Ceq, weld strain, sol. nitrogen, atmosphere and restraint intensity was proposed.