TC4ELI钛合金在3.5%NaCl溶液中的应力腐蚀行为研究  

Research on Stress Corrosion Behavior of TC4ELI Titanium Alloy in 3.5%NaCl Solution

作　　者：李兆峰 蒋鹏 张新杰 晏阳阳 许亚利 孙志杰 LI Zhao-feng;JIANG Peng;ZHANG Xin-jie;YAN Yang-yang;XU Ya-li;SUN Zhi-jie(Luoyang Ship Material Research Institute,Luoyang 471023,China)

机构地区：[1]中国船舶集团有限公司第七二五研究所,河南洛阳471023

出　　处：《材料保护》2023年第3期49-56,共8页Materials Protection

摘　　要：应力腐蚀是海洋装备用钛合金面临的主要威胁之一。为了给海洋装备的安全服役提供技术支撑,以海洋环境用TC4ELI钛合金为研究对象,根据恒位移WOL(楔形张开加载)试样测定KISCC的原理,系统开展了不同组织状态下TC4ELI钛合金在3.5%NaCl溶液中的应力腐蚀行为研究。用光学显微镜和扫描电镜观察了应力腐蚀试样断口形貌和裂纹扩展路径,用二次离子质谱仪分析了裂纹部位元素分布情况。结果表明:TC4ELI双态组织(α相与β相)板材的应力腐蚀门槛值KISCC为56.01 MPa·m^(1/2),魏氏组织板材的应力腐蚀门槛值KISCC大于67.48 MPa·m^(1/2),应力腐蚀试样断口主要由基体、疲劳预制区和撕裂区组成,双态组织试样疲劳预制区与撕裂区界面存在应力腐蚀区,裂纹尖端除主裂纹外还有部分次生裂纹出现;魏氏组织试样未发现明显应力腐蚀开裂特征,魏氏组织的抗应力腐蚀能力优于双态组织的。TC4ELI合金双态组织试样的应力腐蚀开裂以穿晶断裂为主,氢元素易于在裂纹尖端富集。Stress corrosion is one of the main threats to titanium alloys used in marine equipment.In order to provide technical support for the safe service of marine equipment,the TC4ELI titanium alloy used in marine environment was selected as the research object,and its corrosion behavior in 3.5%NaCl solution under different microstructure states was systematically studied by using WOL(wedge⁃open loading)specimen and static displacement method to measure K ISCC.The fracture morphology and crack propagation path of the stress corrosion specimens were ob⁃served by optical microscope(OM)and scanning electron microscope(SEM).The element distribution of the crack site was analyzed by sec⁃ondary ion mass spectrometry(SIMS).Results indicated that the stress corrosion threshold(K ISCC)of duplex microstructure(α+β)sheet was 56.01 MPa·m^(1/2),and the stress corrosion threshold(K ISCC)of Widmannstetter structure sheet was greater than 67.48 MPa·m^(1/2).The frac⁃ture surface of stress corrosion specimen was mainly composed of matrix,fatigue preformed zone and tearing zone.There was a stress corrosion zone at the interface between fatigue preformed zone and tearing zone of duplex microstructure specimen.In addition to the main crack,there were some secondary cracks at the crack tip for duplex microstructure specimen.There was no obvious stress corrosion cracking(SCC)feature in Widmannstetter structure specimen.The stress corrosion resistance of the Widmannstetter microstructure was better than that of duplex micro⁃structure.The stress corrosion cracking of TC4ELI alloy duplex microstructure specimen was mainly transgranular fracture,and the hydrogen was easy to accumulate at the crack tip.

关 键 词：TC4ELI钛合金 双态组织 魏氏组织 应力腐蚀门槛值 裂纹扩展路径 

分 类 号：TG172[金属学及工艺—金属表面处理]