新型1200 MPa级Ti-35421合金应力腐蚀敏感性原位电化学研究  

In-Situ Electrochemical Study on Susceptibility to Stress Corrosion Cracking of New-Developed 1200 MPa Ti-35421 Titanium Alloy

作　　者：曾强强 渠佳慧 淡振华 常辉 周廉 Zeng Qiangqiang;Qu Jiahui;Dan Zhenhua;Chang Hui;Zhou Lian(College of Materials Science and Engineering&Tech Institute for Advanced Materials,Nanjing Tech University,Nanjing 211816,China)

机构地区：[1]南京工业大学材料科学与工程学院&新材料研究院,江苏南京211816

出　　处：《稀有金属材料与工程》2023年第4期1321-1327,共7页Rare Metal Materials and Engineering

基　　金：深海技术科学太湖实验室开放课题(2022JBGS01005);江苏省重点研发计划(BE2019119)。

摘　　要：以新型1200 MPa级Ti-35421合金(Ti-3Al-5Mo-4Cr-2Zr-1Fe)为研究对象,采用慢应变速率拉伸实验结合原位电化学监测研究了不同应变速率和阴极保护电位对其应力腐蚀开裂行为的影响。结果表明:当应变速率为1.67×10^(-5)mm·s^(-1)时Ti-35421合金在3.5%NaCl溶液中应力腐蚀敏感性最高,其塑性损失和应力腐蚀指数分别为27.27%和0.273;裂纹尖端钝化膜层在应力和腐蚀的共同作用下钝化保护弱于溶解,导致了应力腐蚀加剧;当外加阴极保护电位为-600mV时Ti-35421合金在3.5%NaCl溶液中的应力腐蚀敏感性最低,其最佳阴极保护电位范围为-450~-600 mV,降低了阳极共轭反应,从而使其塑性损失和应力腐蚀指数分别降低到1.01%和0.113。The effects of different strain rates and cathodic protection potential on the stress corrosion cracking(SCC)behavior of new-developed 1200 MPa Ti-35421(Ti-3Al-5Mo-4Cr-2Zr-1Fe)alloy were investigated by using slow strain rate test combined with in-situ electrochemical monitoring.The results indicate that Ti-35421 alloy has the highest SCC susceptibility in 3.5%NaCl solution at the strain rate of 1.67×10^(-5)mm·s^(-1).The plastic loss and stress corrosion index of Ti-35421 alloy are confirmed to be 27.27%and 0.273,respectively.The passivating ability of the passivation films in the crack tips is considered to be weaker than active dissolution under the combined interaction of applied stress and corrosive media especially with strain rate of 1.67×10^(-5)mm·s^(-1),which results in the intensification of SCC.When the cathodic protection potential is set at-600 mV,the SCC susceptibility of Ti-35421 alloy in 3.5%NaCl solution is the lowest.The range of the optimal cathodic protection potential is measured to be from-450 to-600 mV.The reduction of the plastic loss and stress corrosion index of Ti-35421 alloy down to 1.01%and 0.113 is ascribed to the slower conjugated anodic reaction kinetics under the cathodic protection.

关 键 词：Ti-35421合金 应力腐蚀敏感性 慢应变速率拉伸实验 原位电化学 阴极保护 

分 类 号：TG146.23[一般工业技术—材料科学与工程]