Reusing the powder across consecutive route cycles is typical in a Selective Laser Melting (SLM) process since it is more sustainable and cost-effective. The theoretical part of the paper is oriented on the explanation of the SLM method principle, construction, and parameters of the device Renishaw AM250 used for manufacturing samples made of AlSi10Mg aluminium alloy. The experimental part focuses on evaluating powders that had been used in the process for a long time with periodic 'rejuvenation'. The main aim will be to monitor whether the samples will be affected and if they achieved the required quality of mechanical properties and compare results with virgin powder and manufacturer sheets for virgin powders. The experimental part further describes the procedures and analysis of the microstructure of the samples. AlSi10Mg aluminium alloy was chosen because of an assumption that it will be sensitive to increased oxygen content. A strong affinity for oxygen uptake exists in AlSi10Mg. Therefore, preventing the contamination, careful handling is required.

The article is focused on the effect of mixing the additional material with the substrate (base material) on the properties of the weld metal during arc welding with TIG technology. The research is aimed at the use of arc welding with TIG technology in the repair of foundry molds. These are repairs of permanent steel foundry molds. The parts of the mold in contact with the liquid metal are subjected to heatchemical-mechanical stress. This load causes mold wear, which causes a decrease in surface quality and a change in the dimensional accuracy of the casting. The main cause of wear on the functional surfaces of the mold cavity is tribological processes. From the study of professional works dealing with mold wear [5,11,22], it is clear that one of the main parameters for determining the intensity of wear is surface hardness. The theoretical part deals with wear and the factors that affect wear. The experimental part compares the properties of one, two, and three-layer TIG welds, specifically the chemical composition, hardness, and coefficient of friction determined by the "ball-on-flat" method.