Powder Metallurgy TC11 Titanium Alloy Via Hot Isostatic Pressing: Preparation, Microstructure and High-Cycle Fatigue Property
GUO Ruipeng1, CHENG Min1, LU Zhengguan2, XU Lei2
1. Taiyuan University of Technology, Taiyuan 030024, China;
2. Shi-changxu Innovation Center for Advanced Materials, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Powder metallurgy through hot isostatic pressing (HIP) route, which is a promising near-net forming method, can fabricate high-performance titanium alloy components with complex structure for applications in the aerospace field. In this study, TC11 pre-alloyed powder was made by electrode induction melting gas atomization method, and the asreceived powder was characterized. The powder compacts were HIP at 940 ℃/140 MPa /3 h from the pre-alloyed powder. The microstructure of as-HIPed powder compact was observed by OM and SEM, and the mechanical properties were evaluated by tensile, impact and high-cycle fatigue tests. The effect of residual micro-pores induced by the hollow powder with gas bubbles on fatigue life of as-HIPed powder compact was also investigated. The results show that the TC11 powder compact is approaching to full density, and the microstructure is fine and homogeneous. The quasi-static mechanical properties of as-HIPed powder compacts are close to or even better than those of wrought alloys. The rotating bending fatigue strength is about 590 MPa at 107 cycles. However, the duality of the high-cycle fatigue S – N curve is observed. The micro-pores located at the surfaces of specimens will preferentially become crack initiation sites under fatigue loading conditions, which will further significantly reduce the high-cycle fatigue life of the powder compacts.