Hierarchical design principles of selective laser melting for high quality metallic objects

Selective laser melting (SLM) is becoming a powerful additive manufacturing technology for different industries: automotive, medical, chemical, aerospace, etc. SLM could dramatically narrow the time frames to optimize production, providing extraordinary freedom to validate design and to develop new materials. The extension of applications requires different materials with specific properties and therefore tailored properties of the final product. In this article, a hierarchical approach including mutual analysis of SLM parameters necessary to control the final product quality on every level - the track, the layer and the final 3D object - is suggested and discussed. Numerical simulation allowed the estimation of temperature distribution during laser melting and predicted final microstructures and properties of a 3D SLM object. A series of single tracks, layers and 3D objects were manufactured from AISI 420 stainless steel to validate a proposed algorithm. The efficiency of the approach was illustrated by the manufacturing of fully dense samples from AISI 420 stainless steel widely used in the plastics-moulding industry. The results show that based on the proposed systematic hierarchical approach, optimal process parameters can be efficiently established for high-quality SLM parts from metal powders.