The enormous growth in additive manufacturing technologies enables a premium fabrication of different high-performance metals and metallic alloys. For industrial applications, a high number of material and process parameters needs to be optimized in order to ensure the quality of the printed parts. One of the key interests is the property comparison of materials fabricated by 3D printing and by conventional manufacturing technologies.

Selective laser melting (SLM) is a commonly used technology for 3D printing of a wide range of metals and metallic alloys. The SLM process with its high solidification and cooling rate as well as cyclical reheating has a significant impact on the final properties of printed materials. Well understanding of the correlation between SLM process and material properties will help to improve the process robustness and reliability and to fulfil the product requirements.

The aim of this study is to investigate the effects of the SLM process, as well as the influence of subsequent heat treatments, on microstructure and properties of the printed materials. For this purpose, two industrial 3D printed metallic alloys (Ti6Al4V, AlSi10Mg) were chosen and analysed. The microstructure was examined using optical and scanning electron microscopy (SEM). The pore size distribution was analysed using ImageJ software and Vickers hardness in the macro and micro range was determined.

The results show that the microstructure of additively manufactured metallic alloys differs fundamentally from that of conventionally manufactured alloys. The layered structure, rapid cooling and cyclic reheating of SLM process cause a characteristic microstructure and phase formation of printed materials. The titanium and aluminium alloys acquire a strength-enhancing structure during the printing process, which can be further optimised by an additional heat treatment. Based on the results feedbacks to the production process can be provided.