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陆莹,乔红超,曲楠,赵吉宾.钛合金焊缝组织循环热处理及球化过程分析[J].稀有金属材料与工程(英文),2019,48(1):254~262.[LuYing,Qiao hongchao,qunan and Zhao jibin.The Cyclic Heat Treatment and Analysis on Spheroidizing Mechanism of Titanium Alloy Welding Microstructure[J].Rare Metal Materials and Engineering,2019,48(1):254~262.]
The Cyclic Heat Treatment and Analysis on Spheroidizing Mechanism of Titanium Alloy Welding Microstructure
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Received:May 04, 2017  Revised:July 17, 2017
DOI:
Key words: TC4 Titanium alloy  welding microstructure  cyclic heat treatment  spheroidizing mechanism
Foundation item:国家基金委-辽宁省联合基金(项目号U1608259);国家自然科学基金(项目号51501219)
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LuYing,Qiao hongchao,qunan and Zhao jibin  
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Abstract:
      Considering the problem of coarse microstructure and awful mirco-orientation distribution of TC4 titanium alloy welded-joint with high friability and low plasticity, we designed the post welding cyclic heat treatment between α+β and β-tansus temperature, and discussed the effect of different heat treatment process on the tissue morphology. The equiaxial alpha phase and lamellar alpha and transformed beta phase composition of the tri-modal microstructure was obtained. The study found that improving the cyclic times, occurrence of alpha phase could increase, and the ratio of length to diameter decreased.However, after five cycles some crystal orientation to meet the lamellar related to α Burger orientation relationship of abnormal growth, lammelar alpha rest staggered phase well-distributed, whereas equiaxed alpha phase is not conducive to improve the mechanical properties. When the clcyic times inceased, the more spherificated α phase appeared, and the length to diameter ratio reduced significantly, generally was less than 3. In addition, there were different kinds of small bars α phase around spherificated α phase. After four cyclic heat treatment, the product of strength and elongation of welded joint achieved 14441.17 MPa?%. The mechanical tests result showed that, after four times of cyclic heat treatment the plasticity of welded joint fracture are at maximum, compact size uniform dimples, have obvious ductile fracture characteristics. Almost at the same time, the yield strength and significantly increased, combined with analysis of EBSD, TEM test results, explain the causes of the phenomenon, and a detailed description of the changes in circulation process and spheroidizing mechanism.