The effect of heat treatment on microstructural and mechanical properties of additive manufacturing and laser welded Tİ6AL4V material

The interest in additive manufacturing technology has been increasing in recent years. Unlike traditional manufacturing methods, the additive manufacturing technique is based on the principle of creating part geometry by adding material instead of reducing material. The advantages of the additive manufacturing technique are the freedom of design, the absence of residual material, the ability to manufacture custom-made products, the low transition time from design to manufacturing, and the ability to obtain lighter products with cellular structures and optimum designs. In addition, the additive manufacturing technique has some disadvantages. One of them is the limited size of the products produced by additive manufacturing. One of the preferred effective techniques to overcome this problem is the welding method. The welding method gives positive results especially in joining metal materials. In this study, the effect of heat treatment on the microstructure and mechanical properties of Ti6Al4V material produced by additive manufacturing and combined with laser welding was experimentally investigated. While determining the heat treatment temperatures, the transformation temperatures of the α and β phases in the structure of the Ti6Al4V material were effective. An optical microscope, SEM, EDX, and XRD experiments were applied to detect the microstructural change. Microhardness and tensile tests were carried out to determine the mechanical properties. To compare the additive fabricated sample with the conventionally fabricated sample, the rolled Ti6Al4V material was also laser-welded and heat treated. In addition, the effect of anisotropy, which is one of the properties of the parts produced by additive manufacturing, was also investigated within the scope of the study. At the end of the study, it was determined that the heat treatments applied to the laser-welded SLE Ti6Al4V material helped improve the material's mechanical properties. Welding efficiency was observed between 69.3% and 83.5% in welded SLE samples. The best elongation values were observed in unwelded SLE specimens. It was observed that both ductility and strength increased especially after heat treatment above the β transformation temperature.