Laser welding of selective laser melted Ti6Al4V: Microstructure and mechanical properties

Ti6Al4V alloy exhibits an excellent potential for biomechanical applications as well as structural engineering applications, especially in the aerospace industry and marine applications. In this study, the effect of laser welding (LW) on grain structure and the mechanical properties in a selective laser melted (SLM) Ti6Al4V is reported. The studied material was SLMed at two different layer thicknesses t , 30 and 50 mm, and respective energy densities 69.4 and 60.3 J/mm(3). Post-annealing treatment at 940 degrees C for 4 h was carried out to relieve stress, induce the b-phase and reduce the acicular a martensite content, thereby helping to enhance its mechanical properties. Subsequently, LW was employed to join SLMed Ti6Al4V plates using a 2.4 kW laser travelling at 60 mm/s. The microstructures were studied as-built by SLM and after LW, followed by an evaluation of the mechanical properties. X-ray diffraction (XRD) and optical microscopy were applied for phase analysis and uniaxial tensile tests were conducted to study the joint strength. The most relevant results of the present work are that the layer thickness plays a key role on tensile properties of the SLMed Ti6Al4V. The SLMed material with t = 50 mm showed higher strength with yield strength 940 MP and ultimate strength 1130 MPa, while the corresponding properties of t = 30 mm were 910 MPa and 1080 MPa, respectively. However, the fracture elongation of the as-built materials with t = 30 mm was 15% as compared to 9% in the higher t . The tensile results of the laser welded materials did not reveal loss in the mechanical properties at both t . (C) 2019 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the 2nd International Conference on Recent Advances in Materials & Manufacturing Technologies.