Effects of High-Temperature Deformation and Welding on Microstructure and Thermomechanical Properties of Ti-6Al-4V

Abstract

The present work investigates the thermal and mechanical behavior of Ti-6Al-4 V alloy across a temperature range from room temperature to 1000 °C, focusing on its application in welding and hot-processing simulations. The study examines temperature-dependent properties, such as phase transformation, thermal expansion, density, and specific heat capacity, with a specific emphasis on the α (hexagonal close-packed, HCP) to β (body-centered cubic, BCC) phase transformation around 800 °C. Various testing methods, including tensile testing, dilatometry, and differential scanning calorimetry (DSC), were used to generate data for these properties. The results show a marked decrease in density and mechanical strength at elevated temperatures, with notable shifts in thermal expansion and heat absorption trends during the α to β phase transition. Microstructural analyses of welded samples reveal distinct regions: the base metal, heat-affected zone, and fusion zone, each showing unique thermal responses and mechanical characteristics. In particular, the HAZ exhibits grain coarsening and reduced mechanical properties, while the FZ displays a dendritic β-phase structure with increased hardness but reduced ductility. These findings provide a detailed database for the thermomechanical modeling of Ti-6Al-4 V alloy, supporting more accurate simulations of welding and hot deformation processes, essential for optimizing performance in high-temperature applications.