Hydrogen diffusion and its effect on ductility of a secondary hardening steel have been investigated by means of Thermal Desorption Spectrometry (TDS) and slow strain rate tensile tests (SSRT). Results show that the hydrogen diffusion coefficient in the investigated steel is 3. 42 X 10-!cm2 · S-1 , and it is evidently lower than those in usually quenched and tempered martensitic steels, which is presumably due to lots of fine carbides in the steeL TDS analysis shows that there are two hydrogen desorption peaks and the desorption activation energy values are 20. 2kJ· mol-1 and 24. 6kJ·mol-1' respecilvely, which are caused by weak hydrogen traps such as grain boundaries and dislocations. The reduction of area of the SSRT specimen decreased linearly with the hydrogen content When the hydrogen content reached 5 × 10-4% , the reduction of area was less than 10% , and the fracture surface was intergranular.%利用升温脱氢分析装置(TDS)和慢速拉伸试验方法(SSRT)研究了一种二次硬化钢中氢的扩散行为及其对塑性的影响.结果表明,由于二次硬化实验钢中存在大量细小碳化物,氢的扩散系数约为3.42x10-8cm2·s-1,明显低于通常淬火回火马氏体钢.TDS分析发现,实验钢中存在两个氢逸出峰,激活能分别为20.2kJ·mol-1和24.6kJ·mol-1,由晶界、位错等弱氢陷阱引起.拉伸试样的断面收缩率随氢质量分数的增加先线性下降,氢质量分数每增加1×10-4％断面收缩率下降约12％;当氢质量分数达到5×10-4％时,断面收缩率低于10％,断口呈沿晶状.
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