Selective electron beam melting (EBM) is a layer-by-layer additive manufacturing technique that shows great promise for fabrication of medical devices and aerospace components. Before its potential can be fully realized, however, a deeper understanding of processing-microstructure-properties relationships is necessary. Titanium alloy (Ti-6Al-4V) samples were built in a newly developed, unique geometry to allow accurate investigation of the following intra-build processing parameters: distance from the build plate and part size. Microstructure evaluation (qualitative prior-β grain size, quantitative α lath thickness), tensile testing, and Vickers microhardness was performed for each sample. Microstructure and mechanical properties were not found to vary as a function of distance from the build plate, which was hypothesized to be influenced by the build plate preheating associated with the EBM process. Part size was found to influence UTS and YS by less than 2% for the size range investigated. A second order effect of thermal mass might also have influenced these results. Differences were observed between the EBM Ti-6Al-4V microstructure of this work and the expected acicular or Widmanstätten microstructure, which might have affected the relationship between α lath thickness and mechanical properties.
Citation: Materials Science and Engineering A-Structural Materials Properties Microstructure and Processing
Pub Type: Journals
Electron beam melting, titanium alloy, tensile, microhardness, microstructure