中文摘要：

车轮钢在恒应力下充氢表面出现氢鼓泡的临界电流和无应力试样相同，恒应力下临界可扩散氢浓度Cσ^＊落在无应力试样的分散带内，t检验表明应力对C0^＊没有影响．恒应力下发生氢致滞后断裂的门槛电流密度和门槛可扩散氢浓度分别为ith=3mA／cm^2和Cth=O．52×10^-6，远小于出现氢鼓泡的相应值ic=5mA／cm^2和C0^＊=1．18×10^-6．无应力时，氢鼓泡并不择优沿夹杂产生；但在恒应力下，氢鼓泡择优沿长条状夹杂形核，其临界可扩散氢浓度从1．18×10^-6降为0．56×10^-6。

英文摘要：

The critical current density for the blistering formed on the surface of wheel steel during charging under sustained stress is the same with that of the sample without stress, and the critical diffusible hydrogen concentration for forming blistering under sustained stress, Cσ^＊ is located within the scatter interval of C0^＊ for the sample without stress, t test shows that there is no effect of the stress on C0^＊. However the threshold current density and diffusible hydrogen concentration for hydrogen- induced delayed fracture under sustained stress are ith=3 mA/cm^2 and Cth=0.52×10^-6, respectively, which are smaller than the corresponding values for forming hydrogen blistering, ic=5 mA/cm^2 and C0^＊=1.18×10^-6. Hydrogen blistering did not preferentially form along the inclusions for the samples without stress, however, the blistering preferentially formed along the lengthened inclusion under sustained stress, resulting in decreasing C0^＊ from 1.18×10^-6 for the samples without stress to 0.56×10^-6 in the sample containing lengthen inclusion under sustained stress.