Microstructure and Tensile Properties of Hybrid Manufacturing TC4 Titanium Alloy
ZHU Yanyan 1 , 2, 3, LI Chong 4 , LIU Yuting 1, 2, TIAN Xiangjun 1, 2
(1. Research Institute for Frontier Science, Beihang University, Beijing 100191, China; 2. National Engineering Laboratory of Additive Manufacturing for Large Metallic Components, Beihang University, Beijing 100191, China; 3. Ningbo Institute of Technology, Beihang University, Ningbo 315800, China; 4. Huaxin Institute for Education Research, Publishing House of Electronics Industry Company Limited, Beijing 100036, China)
Abstract：The hybrid manufacturing technique combining forging and selective laser melting techniques provides an effective approach for the manufacturing of complex integral titanium alloy component with high efficiency and low cost. The microstructure and properties controlling method of hybrid manufacturing titanium alloys is very important for the engineering application. The microstructure and mechanical properties of hybrid manufacturing TC4 samples of two typical process parameters with the layer thickness of 30μm and 60μm of selective laser melting were studied by means of metallographic and microscopic observation, room tensile testing and fractography observation. The results showed that the layer thickness has no effect on the microstructure and properties, however, larger layer thickness can increase the forming efficiency. The gradient microstructure in the bond zone of hybrid manufacturing TC4 is consist of the martensite structure in additive zone and equiaxed structure in substrate zone. There is no obvious heat affected zone in the forging substrate. The micro hardness of additive manufacturing zone is higher than that in the forging zone. The tensile properties of hybrid manufacturing TC4 can satisfy the requirement of the forging standard. The tensile strength of the bond zone is between the additive manufacturing zone and forging zone, but the elongation is equal to the additive manufacturing zone. Due to their different strength and ductility, it is concluded that a shear stress in the interface of gradient microstructure bond zone would form to adjust the deformation in this research. The fractography of the bonding zone tensile specimen is consist of quasi cleavage morphology in the additive manufacturing half zone and dimple morphology in the forging half zone.