鋼材溶接継手の疲れ強さ改善に及ぼす侵入型固溶元素の影響

抄録

Authors have already reported that fatigue strength of structural steel welded joint was improved by rapid cooling from below A₁ temperature, and that this improvement depended mainly on quench aging of interstitially disolved atoms. But the amount of them may be decreased by such heat-treatment when as-received steel has more disolved atoms than solid solution limit at heat-treatment temperature.
Therefore, in this study, the effect of interstitially disolved atoms on fatigue strength improvement of welded joint by such heat-treatment for some steels and the amount of interstitially disolved atoms in as-received SS-41 steel were investigated by fatigue test and internal friction measurement.
Results obtained were as follows;
1) Fatigue strength of welded joint of SS-41, SM-41, and SM-50 steels were remarkably improved by rapid cooling from 700°C.
2) By succeeding aging at 50°C, fatigue strength of SS-41 steel welded joint had much disolved atoms were improved, but that of SM-50 steel welded joint had fewer disolved atoms were not improved.
3) The amount of interstitially disolved atoms in as-received SS-41 steel was almost equivalent to solid solution limit at room temperature.