Microstructure and mechanical properties of TC4 titanium alloy created by selective laser melting technology

Abstract Selective Laser Melting (SLM) technology is applied to create porous TC4 titanium alloy. Then, characterization techniques such as Scanning Electron Microscope (SEM) and Optical Microscope (OM) are applied to conduct microstructure and phase analysis of the layer, HV-1000 micro Vickers hardness tester is applied to test the microhardness distribution among the cross section area of the layer. Furthermore, the influences of the laser power (185, 205, 225, 245, 265 W) and the scanning rate (900, 1000, 1100 mm·s -1 ) on the microstructure and mechanical properties of the TC4 titanium alloy during the printing process is analyzed. The result shows that TC4 titanium alloy is mainly composed of fine needle-like martensite α’ phase and a small amount of β phase, the defects of TC4 titanium alloy created by SLM decrease as the laser power increases, the β columnar crystal grains get thinner and the average length of the needle-like martensite α’ decreases as the scanning rate increases. Under the conditions of laser power being 265 W and scanning rate being 1100 mm·s -1 , the amount of defects reaches the minimum, the bonding is good, and there are Widmanstatten structures composed of fine needle-like martensite α’ and β phases and a clustered structure composed of needle-like α’ phase in the bonding area.