Study On Process Optimization And Property Of Titanium Alloy Manufactured By Selective Laser Melting

Missing and injuery of the teeth is a facing problem to be solved for elderly and even middle-aged people. Selective laser melting(SLM) technique can form the biological tissue with complex shape quickly and easily, and it can perfectly meet the needs of production and industrialization of artificial dental implant. In this paper, the orthogonal optimization analysis of main parameters of the SLM forming Ti6Al4 V alloy has been carried out. The effects of different process parameters on the properties of the Ti6Al4 V alloy were studied. The friction and wear properties of Ti6Al4 V alloy formed by SLM and cast were explored. And dental implant parts of Ti6Al4 V alloy were analysed from the overall and local aspect.The parameters such as laser power, scanning speed and hatching space were optimized by orthogonal experiment. And laser power with 200 W, scanning speed with 500mm/s and hatching space with 0.09 mm are the optimal process parameters. Through the analysis of variance, it can be concluded that the influence of the parameters on the relative density, tensile strength, surface roughness and microhardness is different.The properties of the parts formed by SLM are significantly influenced by the inclination angle. With the increase of the inclination angle, the relative density increases at first and then decreases, reaching a minimum value of 97.34% at 30°, and reaching a maximum value of 98.42% at 90°. The tensile strength and microhardness increase at first and then decrease, and reach a maximum value of 1483.8MPa, 488.9HV at 45°. Surface roughness firstly increases and then decreases, then presents the trendency of increase and then decrease again, reaching a minimum value of 8.5μm at 0°, reaching a maximum value of 19.2μm at 30°. The microstructure of Ti6Al4 V alloy are composed of α’ martensite with lamellar structure and(α+β) phase, and α’ martensite distributes along the Z axis in a columnar. Owing to the low plasticity, the fracture mode of the materials is a coexistence of shear fracture and cleavage fracture.The properties of the parts formed by SLM are critically influenced by scanning speed and hatching space. With the scanning speed increasing, the relative density increases at first and then decreases, reaching the minimum value of 95.50% at 400mm/s, and the maximum value of 97.73% at 500mm/s. With the increase of hatching space, the density increases at first and then rises slowly, reaching the maximum value of 97.73% at 0.06 mm and the minimum value of 96.14% at 0.09 mm.The friction coefficient of Ti6Al4 V alloy increases rapidly, then fluctuates slowly to be constant with the time. The friction coefficient of Ti6Al4 V alloy by SLM fluctuates between 1.1 and 1.3, while the friction coefficient of Ti6Al4 V alloy by casting ranges from 1.0 to 1.1. The fretting wear mechanism of Ti6Al4 V alloy are mainly adhesion wear and abrasive wear, however, the Ti6Al4 V alloy formed by SLM is more significant on abrasive wear.In the preprocessing stage, the dental crown parts were inverted and the tooth nail parts were placed vertically, and the corresponding support was added. The parts were formed with the optimal parameters, and the dimensional accuracy of the dental crown are between 1.12% and 2.49%, while the thread of tooth nail parts are about 3.14%, and surface property is excellent.