The development of alloys adapted to additive manufacturing (AM) processing is of high interest, since various industrially established cast and wrought alloys show limited or no AM-processability. Laser powder bed fusion (PBF-LB) is a widely used metal AM technology and requires powder as feedstock. Since powder preparation is energy- and resource intensive, approaches allowing for rapid and successful screening of alloys adapted to PBF-LB prior to powder preparation, are desired.

In this study, an approach based on casting at high cooling rates is presented. It allows to roughly estimate the phase formation and mechanical properties of alloys processed by laser powder bed fusion (PBF-LB). For mimicking the high cooling rates effectively during PBF-LB, centrifugal copper mold casting is applied. This approach is successfully demonstrated by processing two alloys from different alloy systems - a high-performance Fe85Cr4Mo8V2C1 (wt%) tool steel [1] and an Al-Si-based alloy - via three different techniques providing increasing cooling rates: conventional gravity casting (GC), centrifugal casting (CC) and PBF-LB. By comparing the phase contents of martensite, austenite, and carbides in the tool steel, the CC and PBF-LB material demonstrate good agreement, whereas the GC material shows strongly deviating phase fractions. The compressive strength and microhardness follow this trend to a certain extent although the observed features in the microstructure of the tool steel become finer when processed at increasing cooling rate. Such refinement is also presented for the Al-Si based alloy where the morphology and size of the Al-Si eutectic is determined by the cooling rate. This strongly influences the evolution of the mechanical properties. The observed results demonstrate that centrifugal casting is a highly attractive approach for effective material screening and, thus, for designing alloys adapted to PBF-LB-processing.

Acknowledgement: This work was supported by the German Research Foundation (DFG) within the Research Training Group GRK 2868 D³ - project number 493401063.

[1] Kühn et al., Materials 2022, 15(20), 7266; https://doi.org/10.3390/ma15207266