In terms of biocompatible materials, titanium and its alloys stand out from other materials used in medicine. Titanium alloys 3D-printed for implants offer patients a long life span, customizability and excellent material properties to ensure freedom from irritation [1]. It was investigated the heat treatment-affected properties of Ti-6Al-4V α + β titanium alloy made by SLM (Selective Laser Melting) technology. The experiments aimed to reduce the elastic modulus since the elastic modulus of the dental implant installation environment elastic modulus (mandible E = 12.6–21 GPa) and the elastic modulus of the base material (Ti-6Al-4V) of the implant (110–130 GPa) show a significant difference. The elastic modulus is very important in the implantation because the implant several times replace a human bone [2]. In addition, keeping the corrosion resistance against environmental influences was also an important consideration. The specimens were heated in similar steps to equilibrate the core-to-surface temperature to temperatures below Tβ (650 °C for 10 min, 850 °C for 10 min, and 950 °C for 25 min). It was then cooled to room temperature at high speed using high-pressure N2 gas for 18 min. The three specimens were age-hardened at different temperatures (450 °C or 600 °C, for 130 min). The results of the microscopic examination clearly show that the SLM fabricated specimens developed an α′ needle martensitic microstructure, which transformed into an α + β Widmannstätten microstructure upon heat treatment. The Vickers Hardness test result confirmed the microstructure transformation. A hardness reduction of almost 20% was observed in the heat-treated specimens. The elastic modulus determined in the tensile test did not decrease significantly (103–132 GPa). Increased corrosion resistance to HCl was observed in the corrosion tests. The heat treatments applied improved the properties of titanium alloys made by SLM technology in several aspects.