Wire feeding based laser additive manufacturing TC17 titanium alloy

摘要

TC17 titanium alloy is a rich stable element dual + phase alloy whose nominal composition is Ti-5Al-2Sn-2Zr-4Mo-4Cr. It has high mechanical strength, good fracture toughness, high hardenability and a wide forging temperature range. TC17 titanium alloy is principally applied in engine fan blades, compressor discs and thick sectional forging parts. Laser melting deposition by wire feeding is a technology based on the additive manufacturing principal. The fine wire is melted by laser and then deposited on the substrate along the scanning traces during the process; ultimately, three-dimensional parts are deposited and accumulated layer by layer. Compared to powder feeding, the use of wire is advantageous in terms of having a simple feeding mechanism as well as a higher deposition rate. Generally, the melting state of titanium alloy wire is mainly influenced by laser power, wire feeding speed and scanning velocity. The main focus of the experimental investigation is to find the basic process characteristics. For this purpose, this paper indicates the effect of these parameters on the microstructure, internal defects, heat affected zone, microhardness, microroughness and morphology of single beads through a surface response experiment, and then optimises the laser melting deposition process of TC17 titanium alloy; furthermore, thin walled structure samples are prepared by the optimised parameters.