Influence of Energy Density on Energy Demand and Porosity of 316L Stainless Steel Fabricated by Selective Laser Melting

Selective laser melting (SLM) is one of the most widely used metal additive manufacturing technologies in producing high density parts. Energy density, a key-parameter combination, has been recognized to have a relationship with part formation, but such a relationship is extremely complex. This work aims to investigate energy density as a measure to evaluate energy demand in fabricating pore-free 316L stainless steel SLM parts. Key parameters in energy density were considered in the developed energy demand model. The impact of energy density on the porosity was analyzed with the data from experiments and existing works. Either low or high energy density can result in larger and more pore formation, and the influencing parameter was laser power, followed by layer thickness, scan speed, and hatch space. An effective energy-optimal ((EO)-O-2) zone was proposed, where a relationship between energy density and porosity was developed. It is suggested that high laser power with high scan speeds can deliver energy to a thicker layer with relatively stable melt pool, fabricating high density parts. Hatch space can be decided accordingly to actual melt pool formation. This combination can effectively reduce energy density, and corresponding energy demand.