Novel Quantification of Non-convex Grain Morphology in Printed Ti–6Al–4V

Abstract Complete and accurate quantification of additively manufactured microstructures, along with all their relevant features, is essential for reliable model development, calibration and qualification. This study analyzed trends in grain size and shape in a set of orientation maps acquired from samples of LPBF Ti–6Al–4V printed with varying power and scan speed, all within the process window. The EBSD maps of the $$\alpha $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>α</mml:mi> </mml:math> phase were used to reconstruct the parent $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> grain structure. Fitting a convex hull around each $$\beta $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>β</mml:mi> </mml:math> grain and computing solidity was found to be effective in capturing the non-traditional morphology of the AM microstructures and their asymmetry with respect to the build direction. An equivalent synthetically generated microstructure with similar grain size and aspect ratio was used for comparison of the developed metrics between it and the AM-fabricated samples. The comparison shows that the aspect ratio fails to capture the morphological complexity of AM microstructures, whereas the new metrics effectively differentiate the two types of microstructures. Other than a slight variation in grain size, the grain shape exhibits negligible variation across the range of processing conditions explored.