Konrad Kosiba¹, Uta Kühn¹ and Julia K. Hufenbach^1,2

¹ Leibniz IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, 01069 Dresden, Germany

² Technische Universität Freiberg, Institute of Materials Science, Gustav-Zeuner-Str. 5, 09599 Freiberg, Germany

Presenting author: Konrad Kosiba; k.kosiba@ifw-dresden.de

Despite high demand for high-carbon steels for tooling applications, the processability of available powders on the market via laser powder bed fusion (LPBF) is still limited, because pre-heating of the substrate is still required. During LPBF, which is a widely used metal additive manufacturing technology, feedstock is exposed to a repetitive series of rapid melting immediately followed by solidification at ultrahigh cooling rates. The process of building-up layers causes non-uniform cooling conditions, whereby the heat is almost entirely extracted through the already solidified material which then also experiences a short-term heat-treatment. As a consequence, large temperature gradients and thermal residual stresses evolve in the solidified part. This behavior can be further complicated by alloy-dependent solid phase transformations, such as the austenite-to-martensite transformation for high-carbon tool steels. Pre-heating the base-plate is not striven by industry to mitigate evolving residual stresses. Therefore, we suggest the development of novel high-carbon steels that can better withstand the harsh processing conditions and are hence adapted to LPBF. 

Here, we present a high-carbon alloy developed for LPBF which can be processed without additional base plate pre-heating. An in-depth characterization allows to further explore the hierarchical microstructure which shows a cellular sub-structure. In addition to mechanical properties, the abrasive wear behavior of the LPBF-fabricated components is studied and the appendant underlying mechanisms revealed. The mechanical and wear properties are compared to the commercially available 1.2379 tool steel (X155CrVMo12-1) which serves as reference.