油气钻采用低成本近α钛合金力学与腐蚀性能研究  

Mechanical and Corrosion Performance of Low-cost Near-αTitanium Alloys for Oil and Gas Drilling

作　　者：何苗霞 燕迟 黄帅 王楚 董月成[1] 李峰[1] 常辉[1] HE Miaoxia;YAN Chi;HUANG Shuai;WANG Chu;DONG Yuecheng;LI Feng;CHANG Hui(Nanjing Tech University,Nanjing,Jiangsu 211816,China)

机构地区：[1]南京工业大学,江苏南京211816

出　　处：《石油管材与仪器》2023年第4期32-36,42,共6页Petroleum Tubular Goods & Instruments

基　　金：国家重点研发计划“苛刻环境能源井钻采用高性能钛合金管材研发及应用-高强韧耐蚀钛合金油套管工业化制造成套技术研发”(编号:2021YFB3700802);国家自然科学基金重点项目“深海极端环境下大型钛合金结构应力腐蚀机理研究”(编号:51931008);江苏高校优势学科建设工程资助项目(PAPD)支持。

摘　　要：设计了一种强度和塑性匹配性高的低成本新型近α合金Ti-6Al-1Mo-2Zr-0.55Fe-0.1B,分别通过金相显微镜、扫描电子显微镜、拉伸试验和电化学工作站研究了铸态和锻态合金的组织结构、力学和电化学腐蚀性能。结果表明:铸态合金微观组织由片层状α和晶间β相组成,屈服强度为711 MPa,抗拉强度为882 MPa,延伸率为7.8%,塑性相对较差,断裂方式为混合型断裂。锻造后合金组织中α相呈现为短棒状,屈服强度和抗拉强度分别提高到911 MPa和966 MPa,延伸率达到16.4%,相较于铸态上升了两倍。电化学试验结果表明:两种状态合金的极化曲线趋势相同,锻态自腐蚀电位高于铸态,阻抗复平面图和阻抗谱数据均显示锻造后合金极化电阻升高,因此相比于铸态合金,锻态试样在3.5%NaCl溶液中的自腐蚀电位和阻抗值提高,腐蚀倾向小,耐腐蚀性能更好。A new low-cost near-αalloy Ti-6Al-1Mo-2Zr-0.55Fe-0.1B with high strength and plasticity matching was designed.The microstructure,mechanical and electrochemical corrosion properties of as-cast and forged alloys were studied by metallographic microscope,scanning electron microscope,tensile test and electrochemical workstation respectively.The results show that the microstructure of the as-cast alloy consists of lamellarαand intergranularβphases,with yield strength of 711 MPa,tensile strength of 882 MPa,elongation of 7.8%,relatively poor plasticity and a mixed fracture mode.After forging,theαphase of the alloy is in the form of short bars,and the yield strength and tensile strength are increased to 911 MPa and 966 MPa,respectively,and the elongation is 16.4%,which is twice higher than that of the as-cast alloy.The electrochemical test results show that the polarization curves of the two alloys have the same trend.The self-corrosion potential of the forged state is higher than that of the as-cast state.The impedance complex plane and impedance spectrum data show that the polarization resistance of the alloy increases after forging.Therefore,compared with the as-cast alloy,the self-corrosion potential and impedance value of the forged sample in 3.5%NaCl solution increase,the corrosion tendency is small,and the corrosion resistance is better.

关 键 词：近Α钛合金 微观组织 断口形貌 电化学腐蚀 

分 类 号：TG335.7[金属学及工艺—金属压力加工]