Subsurface Characterization of Heat Treated Subtractive and Additive Manufactured (SLM) Ti6Al4V Specimens

Abstract

AbstractThe widespread use of additive manufacturing (AM) for Ti6Al4V components have demanded an equally extensive study on their comparison with the subtractive manufactured counterparts. Subtractive manufacturing (SM) of Ti6Al4V has its own limitations due to the peculiar properties of the material in the rolled condition. AM process too has its own set of limitations that include porosity, brittleness, and high residual stresses leading to premature failure. Heat treatment (HT) is an option to counter these drawbacks to a certain extent. This study analyzes the effects of HT on the mechanical properties, surface and subsurface characteristics of both AM and SM specimens. A stress relieving process followed by HT above β transus temperature and an aging process enhances the hardness in both counterparts. However, surface levels of SM specimens prove better than AM specimens for wear-resistant applications. AM specimens require the removal of surface to depths between 100 and 200 µm to act as a wear-resistant surface. AM specimens attain a β phase prior to HT and hence a stress relieving operation would suffice in case its being used for applications that require a tough core.KeywordsTi6Al4VSLM printingHTSubsurfaceMicrostructure