**4. Conclusions**

The results of this work substantiated the anisotropy, which is the demonstration of different mechanical properties in different axis, in SLM produced tensile samples even post stress relief. There was an increase in the porosity post stress relief due to the softening of the microstructure subsequent to the precipitation of silicon and Mg2Si during the heat treatment process. Stress relief, however, proved to deteriorate all the mechanical properties accomplished by the SLM process except for the improvement in the ductility/elongation and fatigue life. However, fatigue crack growth and fracture toughness showed that these mechanical properties could be suited for certain applications even though there is a need for the development of the stress relief thermal treatment suitable for additively manufactured materials. SLM produced AlSi10Mg showed to have fatigue resistance after stress relief due to its ductility that could endure pressure from the loading. It is suggested that post SLM thermal treatment for AlSi10Mg be further explored, since seemingly most of these thermal treatments as explored by other researchers' as well demonstrated poor results. Perhaps, looking into developing post SLM rules for heat treatment as compared to using the conventional method rules for SLM produced samples.

**Author Contributions:** Conceptualization, N.R.M.; writing—original draft preparation, B.J.M.; writing—review and editing, B.J.M. and N.R.M.; supervision, L.C.T. and P.AI.P.

**Funding:** The project was funded by the South African Council of Scientific and Industrial Research Parliamentary Grant and the National Research Foundation Grant#114675.

**Acknowledgments:** Council for Scientific and Industrial Research, Tshwane University of Technology, and Metal Heart Additive Manufacturing, are gratefully acknowledged. The authors would also like to thank National Laser Center (NLC) Metallurgical Laboratory and Material Science and Manufacturing Mechanical Testing Laboratory for sample preparation and characterization. The National Research Foundation Grant No. 114675 is acknowledged for funding. Acknowledgement also goes to the following individuals for their support, Thabo Lengopeng, Khoro Malabi, Nana Arthur and Chwayita Madikizela.

**Conflicts of Interest:** The authors declare no conflict of interest.
