回火马氏体钢中氢的扩散行为及其氢脆敏感性

Hydrogen transport behavior and hydrogen embrittlement susceptibility of tempered martensitic steels

通过TDS方法研究了氢在18Cr2Ni4W和25CrNi2MoVNb两种低温回火马氏体钢中的扩散行为,同时结合慢应变速率拉伸实验研究了这两种马氏体钢的氢脆敏感性。结果表明,与18Cr2Ni4W钢相比,25CrNi2MoVNb钢因碳含量较高和晶粒显著细化作用使抗拉强度从1300 MPa级提高到了1500 MPa级后,其氢脆敏感性也明显增加。通过试样充氢后放置试验,测定氢在25CrNi2MoVNb钢和18Cr2Ni4WA钢中的扩散系数分别为7.87×10-7 cm2/s和3.99×10-7 cm2/s。可见,氢在25CrNi2MoVNb钢中更容易扩散,因而在充入相同可扩散氢时,25CrNi2MoVNb钢性能损失更大。

Hydrogen transport in two quenched and tempered martensitic steels 18Cr2Ni4W and 25CrNi2MoVNb was investigated by means of thermal desorption spectrometry（TDS） , and hydrogen embrittlement susceptibility of the steels was investigated by means of slow strain rate tensile tests. Results show that compared with 18Cr2Ni4W steel, 25CrNi2MoVNb steel has a higher strength level of over 1500 MPa due to its higher carbon content and finer grain size,and it also exhibits higher susceptibility to hydrogen embrittlement. From the variation of hydrogen content in the hydrogen-charged specimens with exposing time at ambient temperature, it is found that hydrogen diffusion coefficients in 25CrNi2MoVNb and 18Cr2Ni4W steels are 7.87 x 10-7 cm2/s and 3.99 x 10 7 cm2/s, respectively. Hydrogen can transport more easily in the 25CrNi2MoVNb steel, indicating that the mechanical properties of 25CrNi2MoVNb steel may decrease more evidently when charged with a similar diffusible hydrogen content.