Lore Thijs

Processing AlSi10Mg by selective laser melting: parameter optimisation and material characterisation

Abstract Owing to their attractive combination of mechanical properties, high heat conductivity and low weight, the Al–Si alloys found a large number of applications in the Additive Manufacturing field for automotive, aerospace and domestic industries. However, due to their high reflectivity and heat conductivity, they are harder to process by Selective Laser Melting. This work elaborates on both the optimisation of process parameters, in order to get nearly fully dense parts, and the material properties resulting from this specific material process combination. A process parameter window is defined, in which the formed melt pool is stable and meets the set requirements. In this process window, the parameter set for optimal density is defined. It is shown that AlSi10Mg parts produced by SLM have mechanical properties higher or at least comparable to the cast material because of the very fine microstructure.

Selective Laser Melting of Crack-Free High Density M2 High Speed Steel Parts by Baseplate Preheating

Cracks and delamination, resulting from residual stresses, are a barrier in the world of additive manufacturing and selective laser melting (SLM) that prohibits the use of many metals in this field. By preheating the baseplate, thermal gradients are lowered and stresses can be reduced. In this work, some initial tests were performed with M2 high speed steel (HSS). The influence of preheating on density and mechanical and physical properties is investigated. The paper shows many promising results for the production of SLM parts in materials that are very sensitive to crack formation and delamination. When using a preheating of 200 � C, crack-free M2 HSS parts were produced with a relative density of 99.8%. [DOI: 10.1115/1.4028513]

Microstructural Investigation of M2 High Speed Steel Produced by Selective Laser Melting: Microstructural Investigation of M2 High Speed Steel

In SLM, a high energy density is applied by a laser to locally melt layers of metallic powder particles in order to create functional parts. This high energy intensity and additive process character create a specific/unique microstructure. The solidified melt pools in HSS M2 SLM parts are observed to consist of two distinct zones next to the heat affected zone. The first zone, at the bottom of the melt pool, consists of very fine cells and columnar dendrites and has a hardness of 655±80Hv0.1. The other zone contains acicular martensite and has a hardness of 859±80Hv0.1 which is already similar to the hardness of conventionally produced and heat treated HSS M2. Furthermore, the relative amount of these two zones is observed to be dependent on the scan velocity of the laser and hence can be controlled during the SLM process.