Characteristic length of the solidified melt pool in selective laser melting process

Abstract

Purpose This paper aims to propose methods to evaluate the characteristic length of the melt pool for accurate fabrication and to identify the optimal process parameters in the selective laser melting process. Design/methodology/approach Specimens with the types of the scans by controlling the degree of the overlap with hatch spacing are fabricated. The scan modes are classified by statistically analyzing the results of hardness tests. According to the classification of the scans, the evaluation methods are proposed based on the observation of the shape of the solidified melt pool. Findings The control of the hatch spacing can reproduce all modes of the scan conditions, and hardness can be used to classify the scan modes. Originality/value The proposed evaluation methods are based on the analysis of the experimental observation so that they can be easily used for the real evaluation.

Particle-reinforced metal matrix nanocomposites fabricated by selective laser melting: A state of the art review

“…Photons of a laser beam undergo multiple reflection and absorption in the powder bed system [58,59], characteristics of both affect the laser absorption and resultant melt pool features [60]. Powder shape, size distribution, packing density and thermo-physical properties are essential characteristics which would be greatly influenced by the nanoparticles.…”

Selective laser melting: lessons from medical devices industry and other applications

“…Previous investigations showed that spherical particles are necessary to obtain a good distribution of the powder at the building platform and their variable diameter allows obtaining better adhesion during the fusion process (Casalino et al, 2015;Tang et al, 2018). Due to the significance of the molten pool size for maintaining optimal building conditions, several authors have investigated the effects of laser processing parameters on the molten pool features, either by using modeling techniques (Ahn, 2017;Criales et al, 2016;Chen et al, 2019a;Le et al, 2019;Luo et al, 2018;Wei et al, 2018) or experimentally (Jing and Wang, 2021;Wang, 2018). Moreover, when the scan speed is constant, the geometry of the molten pool will depend on the heat input distribution.…”

Modelling of laser powder bed fusion process and analysing the effective parameters on surface characteristics of Ti-6Al-4V

“…In the case of higher LP and lower SS, the temperature of melt pool increases and stronger Marangoni's effect and flow were observed. The consequences were an unstable melt pool, migration of unmelted powders into the melt pool and increasing S a [65] .…”

“…Therefore, melting flow speed is not zero and higher conduction occurs on the melt pool due to lower conduction effect in overlap and contact regions. Therefore, the size of the melt pool increases and average surface roughness improves [65] ( Fig. 8 shows average surface versus small and big hatch space).…”