The enhancement of process parameters to improve microstructures and mechanical properties of TI-6AL-4V alloy produced by selective laser melting

Abstract

Additive manufacturing (AM) is a powder bed process for the build-up of parts by the distribution of material in which laser power melts the powder layer by layer as generated from a three-dimensional (3D) model design. Selective laser melting (SLM) is an AM method that enables the manufacture of complex geometries, lighter and stronger parts. In this research, the SLM parameters like scanning speed, laser power, and hatching distance were studied using Ti6Al4V powder. The influence of parameters on the surface morphology, surface roughness, and hardness of Ti6Al4V parts was characterised using field emission scanning electron microscope (FESEM), hardness tests, and 3D profiler analysis. In addition, the surface morphology was studied to prove its significance in terms of micropores, balling, and splashing effects. Results showed that the quality of produced parts from SLM was significantly affected by various manufacturing parameters. Hence, the orthogonal array design of experiment was conducted, and statistical analysis with signal-to-noise response was used to obtain the optimal SLM parameters. The experimental outcomes showed that laser power had a high impact on density. Besides, a confirmation experiment was carried out by using optimal parameters (P = 175W, v = 852.5mm/s, and h = 0.13mm) and it was proven that the density increased to 99.933%. The optimal parameter was then implemented to produce body cubic centric (BCC), body cubic centric in Z direction (BCCZ), body cubic centric Z direction in centre (BCCZC), face cubic centric (FCC), and face body cubic centric (FBCC) Ti6Al4V lattice structures. The mathematical modelling, finite element analysis, and experimental studies were conducted to predict and compare the quality of the SLM product. It was discovered that the BCCZ had the highest strength at 5000 MPa. Moreover, the strut and fractured struts were examined to carry out the microcrack and void effect on the strut. The Ashby graph was deployed and the lattice structure was in the range of Ti6 strength. Based on this, the optimal SLM parameters were observed to produce a Ti6Al4V part which had the potential for aerospace, automotive, and biomedical industries. It can be highlighted that this study approached the national policy on Industrial Revolution 4.0 (4IR) through future technologies.