不同硫化物浓度碱性溶液中16Mn钢及热影响区应力腐蚀行为

利用U形弯试样浸泡实验和电化学技术研究了16Mn钢及其模拟热影响区在不同硫化物浓度的碱性(pH=11.7)介质中的应力腐蚀开裂(SCC)行为与机理。结果表明:16Mn钢原始组织、粗晶组织(空冷组织)和硬化组织(淬火组织)在碱性硫化物环境中均能形成保护性腐蚀产物膜、导致电极过程近似呈钝化状态,钝化电流密度依次降低;淬火组织析氢电流密度较高,腐蚀速度较低,长期服役后会造成靠近熔合线部分腐蚀深度大而暴露出残余拉应力区,引起SCC;HAZ中硬化组织、粗晶组织和原始组织在碱性硫化物环境下SCC敏感性逐渐降低,硬化组织具有较明显的SCC敏感性,粗晶组织和原始组织SCC敏感性小;硫化物浓度升高,16Mn钢及其模拟热影响区SCC敏感性增加;16Mn钢焊缝区在碱性硫化物环境中SCC裂纹扩展机制为阳极溶解机制。

Stress corrosion cracking behavior of 16Mn steel and heat-affected zone in alkaline sulfide with different concentrations

This research aims to study the stress corrosion cracking(SCC)behavior and its mechanism of 16Mn steel and heat-affected zone in alkaline(pH=11.7)sulfide solution with different concentrations using electrochemical technology and U-bent specimen immersing test.Original structure,coarse grain structure(air cooling structure)and hardening structure(quenching structure)turned into the state of passivation in alkaline sulfide solution,and the current density of passivation decreased gradually.The current density of hydrogen evolution of hardening organization was higher and corrosion rate was slower.And the corrosion near the fusion line part was deeper and the residual tensile stress area was exposed after long-term service,which caused stress corrosion cracking.The sensitivity of SCC lowered gradually when hardening organization,open grain structure and original structure of HAZ were in alkaline sulfide environment.Hardening structure exhibited high susceptibility to SCC.Coarse grain structure and original structure exhibited low susceptibility to SCC.The susceptibility increased by increasing the concentration of H₂S.The SCC mechanism of 16Mn steel was anodic dissolution(AD)and was intergranular fracturing when it was in the solution of alkaline sulfide.