预应变对DP600钢氢脆敏感性的影响

Effect of Pre-strain on Hydrogen Embrittlement Susceptibility of DP600 Steel

利用慢应变速率拉伸实验(SSRT)及双电解池渗氢实验,结合断口形貌观察和分析,探索了预应变对DP600钢氢脆敏感性的影响规律及机理。结果表明:在本实验预应变量范围内,预应变量小于15%时,随着预应变量的增大,DP600钢试样的氢脆敏感性不断增大,当预应变量达到15%以后,其氢脆敏感性基本趋于稳定。预应变增大了钢中的位错密度,使氢的有效扩散系数降低,有效捕获的氢量增加,从而使钢试样的氢脆敏感性增大;但当预应变量进一步增加至15%以上时,位错的相互缠结减缓氢的扩散和聚集速度,从而使试样的氢脆敏感性增加趋于平缓。

The effect of pre-strain on the hydrogen embrittlement（HE） susceptibility of DP600 steel was studied by means of slow strain-rate tensile（SSRT） test, electrochemical permeation technique and fractograph observation of fracture surface. The results indicate that the HE susceptibility of DP600 steel increases with the increasing pre-strain when the level of pre-strain is below 15%, and then tends to stable when the pre-strain exceeds 15%. The pre-strain increases dislocation density and the amount of effective hydrogen in the steel, but decreases the effective diffusivity（Deff） of hydrogen, so that the HE susceptibility increases. However, when the pre-strain increases to above 15%, the HE susceptibility gradually becomes stable due to the decrease of diffusion and aggregation of hydrogen, which resulted from the dislocation tangle.