Fatigue Improvement of AlSi10Mg Fabricated by Laser-Based Powder Bed Fusion through Heat Treatment

Felix Sajadi,Jan-Marc Tiemann,Javad Mola,Ali Cheloee Darabi,Siegfried Schmauder,Nooshin Bandari

doi:10.3390/met11050683

Felix Sajadi, Jan-Marc Tiemann + Show 4 more

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https://doi.org/10.3390/met11050683

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Journal: Metals	Publication Date: Apr 21, 2021
Citations: 15	License type: CC BY 4.0

Affiliation: University of Stuttgart, Hochschule Osnabrück

Abstract

This study aimed to identify an optimal heat-treatment parameter set for an additively manufactured AlSi10Mg alloy in terms of increasing the hardness and eliminating the anisotropic microstructural characteristics of the alloy in as-built condition. Furthermore, the influence of these optimized parameters on the fatigue properties of the alloy was investigated. In this respect, microstructural characteristics of an AlSi10Mg alloy manufactured by laser-based powder bed fusion in non-heat-treated and heat-treated conditions were investigated. Their static and dynamic mechanical properties were evaluated, and fatigue behavior was explained by a detailed examination of fracture surfaces. The majority of the microstructure in the non-heat-treated condition was composed of columnar grains oriented parallel to the build direction. Further analysis revealed a high fraction of pro-eutectic α-Al. Through heat treatment, the alloy was successfully brought to its peak-hardened condition, while eliminating the anisotropic microstructural features. Yield strength and ductility increased simultaneously after heat treatment, which is due to the relief of residual stresses, preservation of refined grains, and introduction of precipitation strengthening. The fatigue strength, calculated at 107 cycles, improved as well after heat treatment, and finally, detailed fractography revealed that a more ductile fracture mechanism occurred in the heat-treated condition compared to the non-heat-treated condition.

Highlights

Laser-based powder bed fusion of metals (PBF-LB/M), known as selective laser melting (SLM), as one of the highly promising additive manufacturing (AM) processes to produce light metal parts, is a feasible complement to conventional fabrication methods in various industries
PBF-LB/M enables the generation of parts by selectively scanning thin layers of powder metals with a laser beam based on a three-dimensional computer-aided design (CAD) model [1,2]
To minimize the experimental effort and calibrate the heat-treatment process parameters to be applied to the specimens for mechanical tests, heat-treatment conditions associated with maximum hardness were selected

Summary

Introduction

Laser-based powder bed fusion of metals (PBF-LB/M), known as selective laser melting (SLM), as one of the highly promising additive manufacturing (AM) processes to produce light metal parts, is a feasible complement to conventional fabrication methods in various industries. PBF-LB/M enables the generation of parts by selectively scanning thin layers of powder metals with a laser beam based on a three-dimensional computer-aided design (CAD) model [1,2]. One of the commonly used alloys in PBF-LB/M processes is AlSi10Mg. One of the commonly used alloys in PBF-LB/M processes is AlSi10Mg This alloy offers a relatively high fluidity, low shrinkage, and a reduced solidification temperature range, which results in better casting properties [4]. It is classified within the agehardenable alloys, as the addition of Mg enables the precipitation of nanoscale Mg2Si particles and strengthens the alloy [5]. To achieve the desired mechanical properties, heat treatment is usually applied to reach a peak-hardened condition

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