Ⅰ/Ⅱ复合型氢致开裂门槛值的研究

Ⅰ/Ⅱ MIXED-MODE HYDROGEN INDUCED CRACKING THRESHODS

本文对Ⅰ/Ⅱ复合型加载条件下30CrMnSiA钢预充氢试样的氢致开裂门槛值进行了系统的研究。实验结果表明:随着复合比K_Ⅱ/K_Ⅰ的增加,试样的氢致开裂门槛值逐渐增大;Ⅱ型的最大,约为纯Ⅰ型的2.85倍。和理论分析结果相比较,实测的门槛值明显偏高。对复合型裂端氢浓度分布的分析发现:由于位错对氢的捕获和掠夺,使σ_h^(max)处的平衡氢浓度比理论值有所降低,这正是造成实测门槛值偏大的直接原因。

Hydrogen induced cracking thresholds (HICT) of 0.31%C, 0.95%Cr, 0.92%Mn and 1.10%Si steel under Ⅰ/Ⅱ mixed-mode loading condition were studied. Experimental results showed that the mixed-mode HICT increased gradually with increasing K_Ⅱ /K_Ⅰ ratio; Model Ⅱ threshold was 2.85 times bigger as that of pure mode Ⅰ The results from Troiano's hydrogen accumulation theory, however, were apparently lower than the above experimental ones. This phenomenon was mainly caused by the dislocation's hindering effect on hydrogen accumulation at the place where σ_h attained its maximum value.