Metallurgy of additive manufacturing: Examples from electron beam melting

The metallurgy of selected metal and alloy components fabricated by additive metallurgy using electron beam melting (EBM) is presented for a range of examples including Ti-6Al-4V, Co-Cr-Mo super alloy, Ni-base super alloy systems (Inconel 625, 718 and Rene 142), Nb and Fe. Precursor and pre-alloyed powders are preheated and selectively melted using a range of EBM process parameters including beam scan strategies, beam current variations, and cooling rate features. Microstructures and residual mechanical properties are discussed for selected systems in contrast to more conventional wrought and cast products. Novel features of EBM fabrication include columnar microstructural architectures which result by layer-by-layer melt-solidification phenomena.