Selective Laser Melting of a Near-alpha Ti6242S Alloy for High-Performance Automotive Parts

This study aims to investigate additively manufactured Ti6242S specimens compared with the widely used Ti64 alloy with a special focus on microstructure and mechanical properties as well as the impact of subsequent heat treatments. As the Ti6242S alloy, which belongs to the family of near-α Ti-alloys, is often used at higher service temperatures, uniaxial tensile tests are performed at a room temperature up to 500 °C. By means of optical and electron microscopy, it is found that the as-built microstructure consists of acicular α′ martensite, which decomposes to α + β during the subsequent heat treatment. A special focus on the prior microstructure shows that the Ti6242S alloy has a small β grain size, which influences the resulting α′ microstructure after the β → α′ phase transformation. Furthermore, the mechanical properties at room temperature as well as elevated temperatures exceed the values for selective laser melted Ti64 and conventionally cast Ti6242 material. The heat-treated Ti6242S specimens exhibit an ultimate tensile strength of about 1213 MPa including a ductility of 11.3% at room temperature. These values may path the way to a substitution of the widely used Ti64 alloy by the near-α Ti6242S alloy, especially for highly loaded components at elevated temperatures.