Abstract：TC4 titanium alloys are fabricated by laser rapid prototyping(3D printing)， forging and casting.Microstructure and phase composition are analyzed by optical microscope， scanning electron microscope and X-ray diffractometer.The tensile properties are also studied by mechanical performance testing equipment. The results show that the microstructure and properties of the 3D printing titanium alloy have obvious orientation.The strength and elongation of the transverse direction of the sample are 1 013 MPa and 8% respectively， while those of longitudinal direction are 972 MPa and 15% respectively. The strength and elongation of the forging TC4 alloy are 877 MPa and 18% respectively. The strength and elongation of casting TC4 are 836 MPa and 4% respectively. The difference in mechanical properties of samples by different forming methods results from the different microstructures and grain sizes generated by different methods.3D printing TC4 titanium alloy samples form a basket structure during the rapid cooling process.And the grain is very small， about 2-3 μm.The forging sample generated an equiaxed structure with a grain size of about 10 um.And the microstructure is more uniform than 3D printing and casting alloys， thus having a higher elongation.The Widmanst?tten structure is formed in the casting sample， With the grain size up to 20-25 μm， and the tissue distribution is also uneven. Therefore， it has lower mechanical properties.
2019, Vol. 53 
