Exploiting Metastability and Lattice Defects for Microstructural Engineering of SLM Ti-6Al-4V

Kurzfassung

Additive manufacturing (AM) is a technology of enormous potential, yet also of enormous complexity. Unlike “conventional” manufacturing approaches, understanding and exploiting AM requires very interdisciplinary research efforts since material, processing, AM-conformal design & engineering, build strategies, post-treatments and surface finishing are all interdependent. Particularly for load-bearing “class-one” components in space applications, achieving high material quality and performance in a robust AM process such as Selective Laser Melting (SLM) is a major hurdle. The development of different SLM bulk processing and post-heat-treatment strategies for Ti-6Al-4V including intensified intrinsic heat treatment and in situ high-temperature build space heating to obtain stabilized microstructures with fine -particles and films will be presented. Heat treatments act to stabilize the initial as-built microstructures by decomposition of the acicular martensite in conjunction with pronounced element partitioning. New-phase nucleates at prior lattice defects in the as-built microstructures, leading to favorable materials properties. The bulk parameter studies link to development manufacturing strategies, for which further aspects such as parameter-dependence of residual stress (AAMS contribution of T. Mishurova), SLM contour- and downskin processing, and build/support strategies have been studied (AAMS contribution of K. Artzt).