An innovative process of Ti-6Al-4V automotive A-pillars manufacturing using electrically-assisted hot metal gas forming

Ti-6Al-4V material has a wide range of applications in high-performance automotive parts due to its superior mechanical qualities, particularly in the fabrication of automobile A-pillars. However, Ti-6Al-4V tubular components are challenging to manufacture at room temperature. The hot metal gas forming (HMGF) technology is widely used in the manufacture of metals that are challenging to deform, as it enables the attainment of high temperature and pressure during the process of forming. The electrically-assisted hot metal gas forming process (EA-HMGF) may rapidly heat tubular components using Joule heating, significantly decreasing the heating period for hot forming. This study studies the principles and applications of the EA-HMGF process for Ti-6Al-4V tubular components in automobile A-pillars, focusing on three aspects: fundamental mechanical testing, process simulation, and experimental validation of the process. The EA-HMGF simulation model was developed by examining the mechanical characteristics of Ti-6Al-4V material specimens subjected to various strain rates at temperatures ranging from 650 to 750 ℃ under EA heating conditions. Three Ti-6Al-4V tubular components were selected as the object of research, with internal pressures of 35, 40, and 45 MPa applied correspondingly. The simulation model's accuracy was validated by using the thinning ratio of tubular components as the measuring criterion. The results indicated that the range of variation in the tube thinning ratio decreased at a temperature of 700 ℃ and an internal pressure between 40 and 45 MPa. The results indicated that the components essentially adhered to the mold, and the test specimens with intricate local features and overall protruding characteristics could be produced. The feasibility of producing automobile A-pillars using Ti-6Al-4V tubular components is further verified.