阴极极化和应力耦合作用下X80钢氢渗透行为研究

Hydrogen Permeation Behavior of X80 Steel under Cathodic Polarization and Stress

采用改进的D-S双电解池与慢应变速率拉伸实验机相结合,研究了阴极保护和应力耦合作用下X80钢在3.5%Na Cl+1 g/L Na2S溶液中的氢渗透行为。通过变电位氢渗透实验,分析极化电位对氢渗透行为的影响并得到析氢敏感电位。进行不同应力水平下的恒电位极化氢渗透实验,采用Laplace方程分析氢渗透曲线,计算相关的氢渗透参数。结果表明,在各个应力水平下,随阴极极化电位负移,稳态渗氢电流密度增大,析氢敏感电位负于-1000 m V(vs SCE)。在弹性应变时,氢陷阱密度变小,氢扩散系数增大;进入塑性变形阶段后由于位错产生,氢陷阱密度逐渐升高,氢扩散系数降低;吸附氢浓度与扩散系数呈现相反的变化规律。

Hydrogen permeation behavior of X80 steel under applied cathodic polarization and stress in 3.5%NaCl＋ 1 g/L Na2S solution was studied by means of a modified D-S cell combined with slow strain rate tensile machine. The effect of polarization potential on hydrogen permeation behavior and the hydrogen evolution potential were acquired by hydrogen permeation test with changing polarization potential. Besides, potentiostatic polarization hydrogen permeation test under different stress levels was performed and then the hydrogen permeation parameters were calculated by the Laplace equation. Results show that under various stress levels, the steady-state hydrogen permeation current density increased as the cathodic polarization potential decreased, and the hy- drogen evolution potential was lower than -1000 mV （vs SCE）. In the stage of elastic strain, hydro- gen trap density decreased and the apparent hydrogen diffusion coefficient increased. After enter- ing the stage of plastic deformation, hydrogen trap density increased and the hydrogen diffusion co- efficient gradually decreased due to the generation of dislocation. The concentration of adsorbed hydrogen shows a change tendency opposite to the hydrogen diffusivities.