On the Precipitation Hardening of Selective Laser Melted AlSi10Mg

Abstract

Precipitation hardening of selective laser melted AlSi10Mg was investigated in terms of solution heat treatment and aging duration. The influence on the microstructure and hardness was established, as was the effect on the size and density of Si particles. Although the hardness changes according to the treatment duration, the maximum hardening effect falls short of the hardness of the as-built parts with their characteristic fine microstructure. This is due to the difference in strengthening mechanisms.

Improving the fatigue behaviour of a selectively laser melted aluminium alloy: Influence of heat treatment and surface quality

“…Each scan track is outlined by the melt pool boundary that has a coarser microstructure, along with being Al-rich, as demonstrated by having the lighter shade in the optical micrograph in Figure 3 (a). This distribution of the chemical elements has been previously confirmed using energy dispersive X-ray diffraction by the authors in [31]. Cellulardendritic solidification has been previously reported for SLM AlSi10Mg [22].…”

“…Half the samples in each batch were heat-treated following a conventional T6 procedure. The samples were solution heat treated for 1 hr at 520º C followed by water quenching to room temperature and then aged for 6 hrs at 160º C. This was previously shown by the authors [31] to provide the material with increased ductility. As-built and heat-treated samples were cross-sectioned, polished, and etched using Keller's reagent [34] to reveal their microstructures.…”

“…Although heat treating SLM parts is usually guided by the procedures laid out for conventional materials, it is important to note that this might not be generally applicable due to the difference in starting microstructure [21]. The authors of this paper have previously reported [31] an investigation into the heat treatment of SLM AlSi10Mg using a conventional T6 procedure, and observed material softening, rather than the hardening effect that takes place after T6 heat treatment of a conventionally processed AlSi10Mg. They, further, developed an understanding of how to tailor the heat treatment procedure for SLM parts to achieve a particular mechanical response.…”

Nanoindentation Shows Uniform Local Mechanical Properties Across Melt Pools And Layers Produced By Selective Laser Melting Of AlSi 10Mg Alloy

“…Specifically we have been able to link the high hardness to the Si flakes (shown in red in the chemical composition map in Figure 4) with a nanohardness of 9 ± 1 GPa, whilst the surrounding matrix in the as cast material microstructure has a nanohardness of 0.97 ± 1 GPa The melt pool material shows a fine cellular-dendritic structure of α-Al surrounded by inter-dendritic Si (Fig 4(b)). This characteristic microstructure has been previously reported for selectively laser melted AlSi10Mg [11]. The high nanohardness and spatial uniformity of the hardness can be explained by the very fine grain size and uniform Si distribution which are all a function of the fast cooling rate inherent in the manufacturing process.…”

On the Anisotropic Mechanical Properties of Selective Laser Melted Stainless Steel

“…The microstructure of AlSi10Mg revealed clear traces of every single scan track, which inherits an inhomogeneous nature. The Al grain boundaries are surrounded with Si particle segregations, which mainly takes places in the connection between scan tracks and layers, namely hatch overlaps and wetting areas (see Figure 1a) [39,40]. These segregations on the grain boundaries have a stabilization effect and prevent secondary grain coarsening or growth.…”