采用阴极充氢、SSRT缺口拉伸和氢热分析等试验方法，研究了高强度钢42CrMoVNb在不同温度回火状态下的延迟断裂行为，并与常用的机械制造用钢42CrMo进行了对比。结果表明，随着回火温度的升高，试验钢的耐延迟断裂抗力逐渐提高；在相同回火温度下，由于42CrMoVNb钢的强度水平明显高于42CrMo钢，其耐延迟断裂抗力低于后者。在较高的强度水平(大于1250MPa)下，42CrMoVNb钢的耐延迟断裂抗力明显强于42CrMo钢。这主要是由于42CrMoVNb钢在550~650℃的温度范围内回火时析出的细小弥散的(V，X)C碳化物可作为强的氢陷阱而改善钢的耐延迟断裂性能。
Cathodic charging, notch tension and hydrogen thermal desorption analysis test was used to study the delayed fracture behaviors of high strength steel 42CrMoVNb at different tempering temperatures, which were also compared with commercial structural steel 42CrMo. The results show that the delayed fracture resistance of experimenting steels increases with increasing tempering temperature. Since the tensile strength of 42CrMoVNb steel is higher than that of 42CrMo steel at same tempering temperature, the delayed fracture resistance of the former is lower than that of the latter. And in the high strength (more than 1250MPa), the delayed fracture resistance of 42CrMoVNb steel is evidently better than that of 42CrMo steel. This is because there is fine dispersed (V,X)C carbide precipitated in 42CrMoVNb steel when it is tempered at 550-650℃, which is regarded as a strong hydrogen trap and improve the delayed fracture resistance of the steel.
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