Abstract
In this work, Boehler's powder metallurgical high-speed steel (PM HSS) S390 was processed via laser powder bed fusion (LPBF) at different substrate plate temperatures, and the resulting mechanical properties and microstructure were compared. High-alloyed tool steels processed via LPBF are prone to cracking because of their high content of carbon and carbide-forming alloying elements, such as the high-performance PM HSS S390 from Boehler, with 1.64 wt% C and W-Mo-V-Co-Cr (10–2-5–8-5 wt%). Cracks may be induced by thermal expansion and solid phase transformation combined with weak grain boundaries due to the presence of segregated primary carbides. Heating the substrate plate decreases thermal stresses and allows for in situ heat treatment, thus controlling solid phase transformation and carbide precipitation, and preventing cracking during cooling. The resulting microstructure, precipitates, and mechanical properties of the in situ heat-treated specimens (at 600°C and 800°C) and conventionally post heat-treated are presented.
Published Version
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