电化学方法研究X120管线钢氢致裂纹行为

Study on Hydrogen Induced Cracking of X120 Pipeline Steel by Electrochemical Methods

采用Davanathan-Stachursky双电池渗氢装置研究了X120试验管线钢中电化学氢渗透动力学行为,运用电化学充氢方法对X120管线钢进行预制微裂纹,采用SEM观察钢中夹杂物及其与氢致裂纹(HIC)形成的关系。实验结果表明,随着充氢电流密度的增大,饱和阳极电流I∞、氢扩散通量J∞、氢有效扩散系数Deff均逐渐增大;HIC萌生与钢中夹杂物化学成分有关,X120管线钢中主要含有Al、Mn的硫化物、氧化物夹杂,氮化钛、铌的复合夹杂以及Ca-Al-O-S的混合物夹杂,HIC更易于在含Al、Mn的夹杂物处萌生及形成,且裂纹形核后一般沿轧制方向生长。

The electrochemical hydrogen permeation dynamic behavior of X120 pipeline steel was investigated by Davanathan-Stachursky dual cell system. Electrochemical hydrogen charging method was used for prefabricating micro-cracks, and scanning electron microscope（SEM） was employed to observe inclusions and hydrogen induced cracking in X120 pipeline steel. The results demonstrate that the saturated anode current I∞, hydrogen flux J∞ and hydrogen effective diffusion coefficient Deff increase with the increase of charging current density. The effect of inclusions in the steel on the crack initiation depends on their chemical compositions. There are three kinds of inclusions, such as Al/Mn contained sulfide/oxide, Ti/Nb contained nitride complex and Ca-Al-O-S mixed inclusions in the experimental X120 pipeline steel. Hydrogen induced cracking is initiated easily at the sites of Al/Mn contained inclusions, the cracks nucleate and then grow along with the rolling direction.