Influence of different substrates on the microstructure and mechanical properties of WC-12Co cemented carbide fabricated via laser melting deposition

Laser melting deposition (LMD) technology is characterized by a fast-forming speed, additive manufacturing, and a multi-axis operating system, which is suitable for preparing hard alloy parts with complex structures. This study mainly focused on analyzing the microstructure and mechanical properties of cemented carbides fabricated via LMD on different substrates. The results showed that the cemented carbide formed on the WC-20Co cemented carbide substrate had a higher density and fewer cracks and pores compared with fabricating on the 45# steel substrate because the composition of the substrate and powder had similar thermal expansion coefficients, and so the deposition effect was better. The smaller grain size in the microstructure of the cemented carbide formed on a 45# steel substrate was possibly influenced by the difference of liquid phase point and the solid solubility between 45# steel and WC-20Co cemented carbide. Firstly, 45# steel has the higher liquid phase point (1495 degrees C) compared with WC-20Co (1320 degrees C), which made less liquid phase produced during SLM processing. Meanwhile, the solid solubility of WC in 45# steel (7 wt%) is lower than in Co (22 wt%), the dissolution process of WC grains was limited, thus, the growth of WC grains was hindered. Compared with the samples prepared on the 45# steel, the hardness was higher for the alloys fabricated on cemented carbide substrate, which was mainly due to the higher density of the samples and the higher eta-phase.

Automated summary

This study focused on analyzing the microstructure and mechanical properties of cemented carbides fabricated via LMD on different substrates. The results showed that cemented carbide formed on the WC-20Co substrate had higher density and fewer cracks and pores compared to the 45# steel substrate. The smaller grain size in the microstructure of the cemented carbide formed on the 45# steel substrate was possibly influenced by differences in liquid phase point and solid solubility between the two materials.