Effect of laser dwell time on pore elimination in powder bed fusion of metal matrix composites: experimentally validated modeling

Abstract

Many studies have been conducted to better understand the relationship between additive manufacturing (AM) process parameters and the resulting structure and properties of manufactured parts. It is quite clear that defects associated with AM parts are detrimental to part performance and are thus a major concern for a broader application of AM processed parts. In this study, we aim to investigate the influence of process parameters such as laser dwell time in mitigating pore formation during powder bed fusion of AISI 316L austenitic stainless steel (SS316L)-WC composites. Single-track experiments are conducted with varying printing parameters, while discrete element modeling (DEM) is employed for simulating powder-bed packing for composite system. Results show that the filling of the pores between ceramic particles by the molten SS316L is dependent on the laser dwell time, which in turn, depends on the volume fraction of ceramic reinforcement and initial pore sizes between inclusions. Our experiments, in agreement with model analysis, show that with the information of the materials property of the metal phase in a composite system such as viscosity, surface energy and initial pore sizes between ceramic inclusions, the printing parameters can be chosen to yield the appropriate dwell time for pore free composites.

Keywords

• Selective laser melting
• Dwell time
• Porosity
• Composite
• Discrete element modeling