Mechanical properties of alloy Ti–6Al–4V and of stainless steel 316L processed by selective laser melting: influence of out-of-equilibrium microstructures

Abstract

Ti–6Al–4V and stainless steel 316L have been processed by selective laser melting under similar conditions, and their microstructures and mechanical behaviours have been compared in details. Under the investigated conditions, Ti–6Al–4V exhibits a more complex behaviour than stainless steel 316L with respect to the occurrence of microstructural and mechanical anisotropy. Moreover, Ti–6Al–4V appears more sensitive to the build-up of internal stresses when compared with stainless steel 316L, whereas stainless steel 316L appears more prone to the formation of ‘lack of melting’ defects. This correlates nicely with the difference in thermal conductivity between the two materials. Thermal conductivity was shown to increase strongly with increasing temperature and the thermophysical properties appeared to be influenced by variations in the initial metallurgical state.

Keywords:

• Selective laser melting
• Microstructure
• Tensile properties
• Thermal conductivity
• Stainless steel
• Titanium alloys

Acknowledgements

The authors wish to acknowledge the financial support of the European Fund for Regional Development and the Walloon Region under convention FEDER 1784 TipTopLam, and of the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office, contract IAP7/21 ‘INTEMATE’. The authors also wish to thank Mrs S. Salieri and Mr A. Martinez-Aguilera (ULg), and the Additive Manufacturing Team from the Sirris Research Centre for their help with samples preparation.