电化学充氢条件下氢对X80级管线钢力学性能的影响

Effect of hydrogen on mechanical properties of X80 pipeline steel under electrochemical hydrogen charging

应用慢应变速率拉伸试验和扫描电镜(SEM),研究了X80管线钢电化学充氢后的力学性能和断口形貌变化。结果表明:随着充氢电流密度的增大,X80钢中的可扩散氢含量增加,造成伸长率、断面收缩率和冲击吸收能量不断减少,拉伸断口的韧窝变小、变浅,而空洞会增大、增多,空洞边缘出现准解理形貌;电流密度低于5 m A/cm2时,X80钢表面以及其冲击断口无裂纹;电流密度增加至5 m A/cm2以后开始出现裂纹,并且随着电流密度的增加,裂纹开始增大、增多;当电流密度为10 m A/cm2时,冲击断口中出现准解理形貌。

The changes of mechanical properties and fracture morphology of X80 pipeline steel after electrochemical hydrogen charging were investigated by means of slow strain rate tensile test and SEM. The results show that the diffusiable hydrogen content increases with the increasing of hydrogen charging current density,resulting in the decreasing of elongation,reduction and impact toughness. Meanwhile,dimples in tensile fracture become small and shallow,voids become large and more,and quasi-cleavage fractures appear on the edge of voids. When the hydrogen charging current density is below 5 m A/cm2,cracks do not appear on the surface and the impact fracture of the steel; but when it exceeds 5 m A/cm2,cracks begin to appear there and increase with the increasing of hydrogen charging current density.The quasi-cleavage fractures occur when the hydrogen charging current density reaches 10 m A/cm2.