Lack of fusion mitigation in directed energy deposition with laser (DED-L) additive manufacturing through laser remelting

The void level of a component produced by additive manufacturing can be used to predict the mechanical properties and in most cases it is important develop processing methodologies able minimize it. Conventional techniques include parameter optimization hot isostatic pressing (HIP). However, former there limit where improvement becomes minimal latter, although effective for internal voids, not efficient case voids located near surface, which are considered critical. This paper describes study laser remelting was as an alternative achieve higher densification after using directed energy deposition with (DED-L). technique has been investigated powder bed (PB) processes, but explored DED. Understanding behavior different materials considering same parameters also relevant previously addressed. An ytterbium (Yb) fiber maximum nominal power 10 kW wavelength 1070 nm used. Iron Inconel 625 powders were deposited on SAE 1010 steel substrate form beads intentional voids. DED-L performed 450 W, scanning speed 600 mm/min feed rate g/min. radiation applied over surface at three levels: 31.5 kJ/m, 38.2 kJ/m 45 kJ/m. in-house MATLAB image code developed order assess percentage. results indicated that originating from process due lack fusion between deposit substrate. For iron, percentage varied 5.3% 7.1%. After remelting, this value reduced 1.7% applying It noted all samples initially connected coalesced because material redistribution. low repeatability observed. Inconel, 4.4% 7.1%, 3.7% reduction significant observed iron degree dispersion lower iron. Hence, mitigate resultant and, consequently, better quality probability failure. Simultaneously, productivity enhanced since equipment required deposition. new strategies needed increase robustness reduce dispersion.