中文摘要：

车轮钢中自点形成的临界可扩散氢浓度为C0^＊=1．3×10^-6。（总氢浓度CT^＊=3．7×10^-6）．当白点数量超过临界值（对应的可扩散氢浓度Co≥5．6×10^-6），则使强度和塑性急剧下降．但实际车轮中自点含量少（Co〈3．9×10^-6），对材料的拉伸性能和断裂韧性没有影响．原子氢对断裂韧性KIC没有影响；但如慢拉伸，则使塑性下降．如恒位移加载，则原子氢能引起氢致滞后开裂，其门槛应力强度因子KIH随C0升高而线性下降，即KIH=57．8-3．9Co．但白点对氢致滞后开裂没有影响．

英文摘要：

The experiments of atomic hydrogen concentration and appearance of flaking in a wheel steel show that the critical diffusible hydrogen concentration for formation of flaking is C0^＊ = 1.3 × 10^-6 （or total hydrogen concentration CT^＊=3.7× 10^-6）. If the amount of the flaking exceeds a critical value, e.g., corresponding to C0〉5.6 × 10^-6, the plasticity and strength of the steel decrease sharply. In general, for wheel steels, C0〈3.9 × 10^-6, the amount of flaking is below the critical value, thus there is no effect of flaking on tensile properties and fracture toughness KIC. Atomic hydrogen does not influence fracture toughness, but causes plasticity to decrease evidently during slow strain rate tension. Atomic hydrogen can also cause hydrogen-induced delayed cracking under constant deflection loading and the threshold stress intensity factor of hydrogen induced delayed cracking, Kin, decreases linearly with increasing diffusible hydrogen concentration, i.e., KIH=57.8-3.9 Co. However there is no effect of the flaking on hydrogen-induced delayed cracking.