Additive manufacturing or 3D printing is a manufacturing process that is based on adding material layer by layer and represents a new way of manufacturing machine or structural elements.
In this work, selective laser melting (SLM) was used to produce the samples. Among other things, SLM is also used in tooling for the production of die casting tools. SLM allows us to manufacture tool components with conformal cooling that enables optimal tool temperature, which greatly affect the tool life as well as the die casting process (porosity, hot spots, cycle time, possibility of casting more demanding castings, scrap, lubricant consumption etc.). With the aim of shorter production times and lower costs of individual tool components, hybrid production is often used. Hybrid components are made of the traditionally produced lower part of the tool component (base) and the upper SLM part, which contains conformal channels. The traditionally produced tool component part is usually made of tool steel with a different chemical composition, mechanical properties and physical properties. Therefore, the selection of the appropriate heat treatment to ensure adequate mechanical properties of the entire tool component and adequate joint quality is very difficult.
SLM and hybrid samples were produced using the maraging steel powder MS1 (EOS GmbH). The influence of heat treatments on the microstructure and mechanical properties of the samples were analyzed. The main goal was to find the optimal heat treatment of the SLM samples and the optimal base material and heat treatment for hybrid samples. The experimental work consisted of two parts. In the first part the samples were produced entirely with SLM, in the second part the samples were produced hybridly with base materials from tool steel 1.2343 and maraging steel Böhler W720. The samples undergo different heat treatments, consisting of solution annealing and/or aging at different temperatures and different holding times. After heat treatments, the samples were machined, as they were produced with addition of material, because we wanted to get as close as possible to the process of making the die-casting tool components, to which this work relates. This was followed by the sample characterization, where we used methods such as tensile test, Charpy impact toughness test, Vickers and Rockwell hardness measurements, light and electron microscopy (SEM, TEM), X-ray energy dispersion spectrometry (EDXS) and EBSD analysis. The particle size distribution of MS1 metal powder was also determined.
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