Effect of laser parameters on microstructure, metallurgical defects and property of AlSi10Mg printed by selective laser melting

Abstract

AlSi10Mg alloy has been widely used in selective laser melting (SLM). However, the formation of metallurgical defects in this material during SLM process has not been studied sufficiently. In this work, different laser parameters were adopted to fabricate the specimens. The effects of volumetric energy density (VED) on the metallurgical defect, densification, phase composition and mechanical property were also comprehensively analyzed. At low VED of 37.39[Formula: see text]J/mm3, a nearly full dense sample with density of 2.602[Formula: see text]g/cm3 can be printed. The sample with maximal tensile strength of 475[Formula: see text]MPa can be printed. While with the increase of VED, the ultimate tensile strength decreases due to the formation of micro-pores. The formation mechanisms of micro-pores including gas pores and keyhole-induced pores were disclosed from the angle of alloy smelting. Better understanding of the influence mechanisms of the laser parameters on the formation of metallurgical defects is beneficial for the production of high performance SLM parts.

Research on the Thermal Behaviour of a Selectively Laser Melted Aluminium Alloy: Simulation and Experiment

“…Xiao et al found that the gas solubility of the melt pool increased with increasing energy density during laser welds of the Al–Li alloy. In SLM, gas including evaporative magnesium [ 27 ], hydrogen [ 28 ], and argon will dissolve out but be detained in the melt pool under the condition of a low solidification rate; moreover, gas pores diffuse and expand easily, and larger keyhole pores are induced. Weingarten et al [ 29 ] concluded that each time the following layer was scanned, the consolidated material was heat-treated if the penetration depth led to a more partial remelting at high energy density; as such, it is possible to conclude that trapped gas pores can enlarge and reduce the relative density.…”

Effect of melting modes on microstructure and tribological properties of selective laser melted AlSi10Mg alloy

“…Note that the golden V-shaped molten pool (referred as keyhole molten pool, KMP) induced by the keyhole effect only appears in the KM specimen. Moreover, the pores located at the bottom of the KMP (known as keyhole defects) confirms that material vaporisation occurred as a result of the keyhole effect (Wu et al 2017). By comparing the pore defects in two melting modes, it is thought that the hydrogen pores are the main factor affecting the densification.…”

“…The relative density of SLM part under CM (96.68 ± 0.06%) is slightly higher than that of the part under KM (95.52 ± 0.05%), implying that the laser-induced balling effect is not the only reason affecting the density of SLM parts. It has been shown that there are two major defects that have been demonstrated to be the main reason for the density reduction (Wu et al 2017). One is the high concentration of hydrogen pores caused by the humid environment and the high E; the other is keyhole defect induced by high-energy vaporised metals.…”

Microstructure and Corrosion Behavior of Ti-Nb Coatings on NiTi Substrate Fabricated by Laser Cladding

“…With the increase of undercooling, the critical nucleation radius decreased and the nucleation rate increased, resulting in the finer grain sizes of the cladding layer. The fine microstructure would lead to difference in mechanical properties [44]. In a certain range, finer grain structures are beneficial for improving the strength and toughness of materials.…”