Effect of processing parameters on pore structures, grain features, and mechanical properties in Ti-6Al-4V by laser powder bed fusion

In this study, the process-structure-property linkages in laser powder bed fusion of Ti-6Al-4V were investigated experimentally and quantified via correlation analysis. Forty-two different combinations of laser power and scan speed were examined to probe lack-of-fusion, keyholing, and beading-up defect regions in addition to dense regions of the processing space. The resultant structures of the fabricated components were characterized through X-ray computed tomography for visualization and characterization of internal pores and optical metallography to examine prior-β grain features. Mechanical properties were assessed via uniaxial tension tests and Vickers microhardness measurements. Correlation analyses, used to quantify the statistical bivariate relations between feature pairs describing processing conditions, microstructural features, and mechanical properties, revealed the relationship between processing parameters and defect pore morphology, which in turn correlated with mechanical properties. Additionally, the work expands on process maps for avoiding porosity by defining correlations between processing conditions and resultant properties, providing a means for tailoring properties and structures via processing in laser powder bed fusion additive manufactured materials.