回火时间对马氏体钢氢脆敏感性的影响

Effect of tempering time on hydrogen embrittlement sensitivity of martensitic steel

采用慢应变速率拉伸及氢渗透试验研究了回火热处理时间对一种马氏体钢氢脆敏感性的影响。试验结果表明:随着回火时间的延长,试样的氢脆敏感性先降低后增加,当回火时间为4 h时,材料的氢脆敏感性指数达到最低值。其主要原因是当回火时间小于4 h时,大量碳化物的析出有效捕获了氢原子,使有效氢扩散系数及氢脆敏感性均降低;但当回火时间大于4 h时,碳化物粗化长大,其对氢原子的捕获作用减弱,导致有效氢扩散系数增加,氢脆敏感性增强。

The effect of annealing time on the hydrogen embrittlement sensitivity of martensitic steel was studied by slow strain rate tensile and hydrogen permeation tests. The results show that the hydrogen embrittlement sensitivity decreases first and then increases with the extension of tempering time.When the tempering time is 4 h, the hydrogen embrittlement sensitivity index reaches the lowest value.The reason is that when the tempering time is less than 4 h, a large number of carbide precipitates can effectively capture hydrogen atoms, which reduces the effective hydrogen diffusion coefficient and hydrogen embrittlement sensitivity. However, when the tempering time is longer than 4 h, the carbide coarsens and grows up, which weakens the trapping effect on hydrogen atoms, increases the effective hydrogen diffusion coefficient and enhances the sensitivity to hydrogen embrittlement.