Experimental investigation of effect of printing direction and surface roughness on the mechanical properties of AlSi10Mg-alloy produced by selective laser melting

Abstract

The additive manufacturing has initially gained popularity for production of non-loadbearing parts and components or in the fields where the material strength and ductility are less important such as modelling and rapid prototyping. But as the technology develops, availability of metal additive manufacturing naturally dictates the desire to use the produced components in load-bearing parts. This requires not-only a thorough documentation on the mechanical properties but also additional and independent research to learn the expected level of variation of the mechanical properties and what factors affect them. The presented paper investigates strength, ductility, hardness, and microstructure of the AlSi10Mg alloy produced by the selective laser melting (SLM). The mechanical properties were determined through a series of uniaxial tension tests and supplementary hardness tests and rationalized with the microstructure evolution with regard to printing direction and heat treatment. The paper also addresses the effect of surface roughness on the mechanical properties of the material, by comparing the machined and net shape tension samples. As expected, the as-manufactured AlSi10Mg-alloy appears to be a semi-brittle alloy, but its microstructure can be altered, and ductility increased by a proper heat-treatment. The effect of surface layer removal on the measured mechanical properties is of particular interest.

On the Influence of Cross-Section Size on Measured Strength of SLM-Produced AlSi10Mg-Alloy

“…The comparison of different sample sizes and geometries also seems not to have received enough attention in the literature yet. In our earlier work we reported a comparison of strength of SLM-produced AlSi10Mg samples of different diameters [5]. Similar, but more focused study was reported by [6] who compared the strength, the microstructure and the porosity of AlSi10Mg samples of different diameters and reported up to 30% decrease in strength for small struts.…”

“…[8]-[29] Rectangular cross-section samples machined on all sides [3], [30]- [35] Flat cross-section samples cut out of a plate or thin-walled profile [36]- [39] Net shape rectangular cross-section samples that were sandblasted [40] Net shape cylindrical [6], [41]- [43] Mass-produced net shape rectangular samples [44] Understanding the influence of the sample cross-section size on the measured strength is crucial to be able to compare the values of strength reported using different sample geometries. In this article we complement our previous results from [5] with additional study of material microstructure and make a comparison with the results of [6] in order to gain a deeper understanding on how the measured strength and microstructure of SLM-produced AlSi10Mg are affected by the size of printed cross-section.…”

“…The samples in these series were oriented vertically i.e., in the build direction, which allows to 3D-print samples without the need for support structure. Overview of the all 15 series can be found in [5].…”

“…The experimental work reported in [5] and [45] includes 15 sets of uniaxial tension test samples printed in two rounds sets #1-6 in the first round and sets #7-15 in the second round. The samples were printed by SLM®280 metal printer with 400 W laser using 50 μm printing layer thickness and argon gas as protective atmosphere.…”

Assessment of surface waviness of casting patterns made using 3D printing technologies

“…Most of the research concerns the analysis of the influence of print direction on the dimensional and shape accuracy and the quality of the surface layer of the parts produced, taking into account only the change of print direction [15][16][17]. In most studies, the surface texture is examined by analyzing the 2D or 3D roughness parameters or by applying the multiscale method [18,19].…”