Effect of Zero Holding Time in Heat Treatment on the Mechanical and Microstructure Properties of Additive Manufactured Titanium Alloy (Ti6Al4V) through Selective Laser Melting (SLM) Process
Authors:   Advanced Manufacturing Research Group, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Mohd Foudzi Farhana ,   Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Kah Min Moey ,   Advanced Manufacturing Research Group, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia,   Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Jamhari Fathin Iliana ,   Advanced Manufacturing Research Group, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia,   Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Ahmad Buhairi Minhalina ,   Advanced Manufacturing Research Group, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia,   Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia,   Doctoral School on Materials Science and Technologies, Óbuda University, Nepszinhaz u. 8, 1081 Budapest, Hungary, Sulong Abu Bakar ,   Advanced Manufacturing Research Group, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia,   Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Muhamad Norhamidi ,   Advanced Manufacturing Research Group, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia,   Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Mohd Radzuan Nabilah Afiqah ,   Advanced Manufacturing Research Group, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia,   Department of Mechanical and Manufacturing Engineering, Faculty of Engineering and Built Environment, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia, Aziz Izhar ,   3D Gens Sdn Bhd, No 18, Jalan Kerawang U8/108, Bukit Jelutong, 40150 Shah Alam, Selangor, Malaysia, Tan Kim Seah ,   Oryx Advanced Materials Sdn Bhd, Plot 69(d) & (e), Lintang Bayan Lepas 6, Bayan Lepas Industrial Zone, Phase 4, Bayan Lepas, 11900 Penang, Malaysia
Published: June 2024

Additive manufacturing (AM) or better known as 3D printing is a manufacturing method based on powder metallurgy technology that is able to produce a 3D component. Selective laser melting (SLM) is one of the AM methods capable of producing metal 3D components, however, residual stresses are often produced in such component due to repeated melting and solidification of metal during the printing process. The residual stresses can deteriorate the performance of the 3D components’ mechanical properties if not removed or reduced. Heat treatment processes are often used to remove the residual stresses. The basic parameters of heat treatment are heating temperature, heating rate, cooling rate and holding time. Based on the basic parameters, the effect of holding time in heat treatment is still less reported for 3D components printed via SLM. Therefore, in this study, the effect of holding time on the mechanical properties and microstructure of 3D titanium alloy (Ti6Al4V) components was intestigated. A total of 9 sets of cubic samples were printed on different processing parameters such as laser power (225W, 275W, 325W), scanning speed (800mm/s, 1100mm/s, 1400 mm/s), layer height (0.3mm) and hatching distance (0.10mm, 0.12mm, 0.14mm ). It was found that hardness of 383 - 448 HV was obtained where samples P3, P9 and P5 gave the highest, medium and lowest hardness values. Based on the microstructure observation, α + β phase and martensite structures are produced due to the vanadium content of 4% and heat treated at 935°C. A critical review was also studied to compare previous studies that used different holding times on SLM-printed Ti6Al4V 3D components. It was found that different holding times did not have a significant effect on the mechanical properties of Ti6Al4V 3D components where the outcome of previous studies alligns with that of from this study. In addition, past works have also reported that heat treatment is able to lower the residual stresses in SLM-printed Ti6Al4V 3D components. Finally, the effectiveness of heat treatment in reducing the residual stresses in SLM-printed Ti6Al4V 3D components at different printing parameters should also be studied to understand the mechanism of microstructural changes during and after heat treatment.