Texture control of 316L parts by modulation of the melt pool morphology in selective laser melting

Abstract

A B S T R A C TIn this study, 316L parts were fabricated with the selective laser melting additive layer manufacturing process using unidirectional laser scan to control their texture. The melt pool shape, microstructure and texture of three different cubic samples were analyzed and quantified using optical microscopy and electron back-scattered diffraction. The samples scanned along the shielding gas flow direction were shown to exhibit shallow conduction melt pools together with a strong {110} < 001 > Goss texture along the laser scanning direction. The sample prepared with a laser scan perpendicular to the gas flow direction had deeper melt pools, with a weaker {110} < 001 > Goss texture in addition to a < 100 > fiber texture parallel to the scanning direction. Correlations were proposed between the melt-pool geometry and overlap and the resulting texture. The decrease of the melt pool depth was assumed to be linked to local attenuation of the laser beam effective power density transmitted to the powder bed.

A competition between the contour and hatching zones on the high cycle fatigue behaviour of a 316L stainless steel: Analyzed using X-ray computed tomography

“…The powder used to manufacture the samples was a 316L stainless steel, with the composition given in Table 1. The particle size distribution measured was between 15 and 100 μm with a D 50 of 38 μm, similar to the powder batch used in a recent work [22].…”

“…First, a lack of sufficient bead overlap between the starting and end point of one circular contour can occur. Additionally, an interaction between the laser and contaminants such as spatter or nanoparticles in specific laser trajectories could induce heterogeneities in the melt pool shape [22], and thus impact the horizontal or vertical…”

“…Surface roughness, defects and microstructure can be directly related to the building parameters [18][19][20][21][22]. Such parameters usually differ from one zone to another one of the fabricated part.…”

Crystallographic Orientation Control of 316L Austenitic Stainless Steel via Selective Laser Melting

“…The melt pool with a smaller depth/ width ratio, generated in Specimen_B, indicates conduction mode melting. It has been argued that the shape of the melt pool controls the crystallographic texture formation 13,20) because the melt pool shape reflects the temperature distribution; thus, affects the directions of the thermal gradient and solid/liquid interface migration. In the conduction mode, the curvature of the melt pool bottom decreases during solidification, and the migration of the solid/liquid interface is frequently toward the build direction as solidification proceeds.…”

Optimization and comparison of porosity rate measurement methods of Selective Laser Melted metallic parts

“…-A high VED leads to the formation of a vapor plume. The interaction between this vapor plume (generated above the impact zone) and the laser can lead to the formation of porosities [18]. As shown by [19] this vapor plume is composed of macro droplets and nanocondensates which interfere with the laser by absorbing the radiation, hence limiting the bead penetration and possibly promoting LOF.…”