Process Optimization of Additive Manufacturing of Tool Steels

Abstract

Additive manufacturing is one of the growing fields in manufacturing industry. Selective laser melting is one of the techniques based on powder bed fusion and used normally for metallic materials. H13 tool steel is categorized as difficult – to – build materials, because the alloy carbides contained due to high amount of carbon make it difficult to melt and fuse. Another challenge is that the cooling rates in selective laser melting can reach as high as 104-106 K/s, which affects the final properties of the printed part. Furthermore, the process parameters of selective laser melting affect the properties of the material. This work studies the printing behavior of H13 tool steel with different process parameters for selective laser melting. The work aims to obtain the optimum process parameters. For this purpose, 71 samples are prepared and inspected in terms of porosity, microstructure, hardness and density by means of scanning electron microscopy, energy dispersive spectrometry, light optical microscopy and density measurements. It is found that based on layer thickness, laser power, scanning speed and hatch distance can be selected. In conclusion, to achieve good printing results with 45 μm and 60 μm layer thickness, scanning speed and hatch distance should be low with high laser power. For 30 μm layer thickness, laser power and scanning speed should be high and hatch distance should be low.