Wang Wei, Xu Xiaowen, Ma Ruixin, Xu Guojian, Liu Weijun, Xing Fei
School of Mechanical Engineering, Shenyang University of Technology, Liaoning 110870, China.
School of Material Science and Engineering, Shenyang University of Technology, Liaoning 110870, China.
Materials (Basel). 2020 Sep 15;13(18):4087. doi: 10.3390/ma13184087.
Ti-6Al-4V (TC4) titanium alloy parts were successfully fabricated by laser melting deposition (LMD) technology in this study. Proper normalizing temperatures were presented in detailed for bulk LMD specimens. Optical microscope, scanning electron microscopy, X-ray diffraction, and electronic universal testing machine were used to characterize the microstructures, phase compositions, the tensile properties and hardness of the TC4 alloy parts treated using different normalizing temperature. The experimental results showed that the as-fabricated LMD specimens' microstructures mainly consisted of α-Ti phase with a small amount of β-Ti phase. After normalizing treatment, in the area of α-Ti phase, the recrystallized length and width of α-Ti phase both increased. When normalizing in the (α + β) phase field, the elongated primary α-Ti phase in the as-deposited state was truncated due to the precipitation of β-Ti phase and became a short rod-like primary α-Ti phase. In as-fabricated microstructure, the β-Ti phase was precipitated between different short rod-shaped α-Ti phases distributed as basketweave. After normalizing treatment at 990 for two hours with subsequent air cooling, the TC4 titanium alloy had significant different microstructures from original sample produced by LMD. The normalizing treatment methods and temperature can be qualified as a prospective heat treatment of titanium alloy fabricating by laser melting deposition.
本研究采用激光熔化沉积（LMD）技术成功制备了Ti-6Al-4V（TC4）钛合金零件。详细给出了大块LMD试样合适的正火温度。利用光学显微镜、扫描电子显微镜、X射线衍射仪和电子万能试验机对不同正火温度处理后的TC4合金零件的微观组织、相组成、拉伸性能和硬度进行了表征。实验结果表明，增材制造的LMD试样微观组织主要由α-Ti相和少量β-Ti相组成。正火处理后，α-Ti相区域内α-Ti相的再结晶长度和宽度均增加。在（α+β）相区正火时，沉积态的拉长初生α-Ti相因β-Ti相的析出而被截断，变为短棒状初生α-Ti相。在增材制造的微观组织中，β-Ti相在呈交织状分布的不同短棒状α-Ti相之间析出。在990℃保温两小时后空冷的正火处理后，TC4钛合金的微观组织与LMD制备的原始试样有显著差异。正火处理方法和温度可作为激光熔化沉积制备钛合金的一种有前景的热处理方法。
