Experimental Investigation on Hatch Distance of Deposited Layers of AISI 316L Stainless Steel Fabricated by Laser-Directed Energy Deposition

Abstract

Additive manufacturing is a manufacturing technique that offers the potential to fabricate complex structures at a low cost with less energy. Laser-Directed Energy Deposition (L-DED) technology is one of the AM methods that uses a laser beam to melt the powder and the substrate and fabricate an object layer by layer. Hatch distance (HD) is one of the most critical parameters of the L-DED process. The effects of hatch distances of 1.14, 1.08, and 1.02 mm on the microstructure of the AISI 316L stainless steel deposited layers were evaluated. The L-DED process was performed using a 1000 watts continuous wave fiber laser. The microstructure of the AISI 316L deposited layers was evaluated using optical microscopy. The results showed that the most appropriate overlap between the deposited layers was obtained at a hatch distance of 1.02 mm. The results also indicate that the equiaxial and columnar dendritic structure is observed in the L-DED deposited layers at all conditions. The high cooling rates and temperature gradient associated with laser deposition promote the formation of dendrites. Gas porosity defects were observed in some areas of the deposited layers.