Eliminating continuous grain boundary α phase in laser melting deposited near β titanium alloys by heat treatment

2019 International Conference on Advanced Electronic Materials, Computers and Materials Engineering

无线电电子学;计算机科学;材料科学

Li, Penglin^1 ; Liu, Changmeng^1 ; Wang, Jie^2 ; Lu, Jiping^1 ; Ma, Shuyuan^1 ; Fan, Hongli^1

School of Mechanical Engineering, Beijing Institute of Technology, Beijing

100081, China^1

Beijing Institute of Astronautical Systems Engineering, Beijing

100076, China^2

关键词: Beta titanium alloy;    Furnace heating;    Intergranular fracture;    Laser melting;    Near beta titanium alloys;    Nucleation and growth;    Slow heating;    Ti17 alloys;   

Others  :  https://iopscience.iop.org/article/10.1088/1757-899X/563/2/022025/pdf
DOI  :  10.1088/1757-899X/563/2/022025

来源: IOP

【 摘 要 】

Continuous grain boundary α phase (α gb) is widely present in laser melting deposited near β and β titanium alloys, and it can lead to intergranular fracture and low ductility. Because of the preferential nucleation and growth of α phase at β grain boundaries, the continuous α gb cannot be effectively eliminated by traditional heat treatment. Thus, in this study, we develop a new heat treatment including beta solution + ultra-slow furnace heating up + traditional heat treatment, to eliminate continuous α gb in laser melting deposited Ti-5Al-5Mo-5V-1Cr-1Fe near β titanium alloy, and the microstructures and tensile properties are investigated. The results indicated that, after beta solution + normal heating up + traditional heat treatment, the continuous α gb still exists, and the elongation is still low about 7.5%. However, after beta solution + ultra-slow heating up + traditional heat treatment, there are almost no continuous α gb, and the elongation increases to 15.2%. The mechanism about the α gb formation during ultra-slow heating up process is simply revealed. Furthermore, this new heat treatment is also suitable to eliminate continuous α gb for laser melting deposited Ti17 alloy.