The effect of nominal powder thickness on solidification behavior of atypical multilayer WC-Co components fabricated by laser-powder bed fusion

Laser-powder bed fusion (L-PBF) is one of the most innovative powder-based additive manufacturing (AM) technologies that can produce complex geometries based on a CAD profile. Thus, it provides a design freedom capability. However, fabrication of WC-Co parts for cutting tool industry is still facing challenges in AM. Optimum process parameters as well as feedstock characteristics for high-quality microstructures are yet to be reached whereas cracks and pores represent the main drawbacks. In this study, the impact of atypical WCM-Co composite powder was examined in L-PBF process. This involves, for the first time, fabrication of multilayer parts using a nominal powder thickness range of 50-70 mu m. The results revealed a threshold of powder thickness considering the macro-sized solidification cracks; with-when powder thickness was < 70 mu m and without-when powder thickness was 70 mu m. However, this value has also led to increase the number and size of macro-sized pores. Moreover, the results also showed a partial dissolution of the original carbide particles which has led to produce three W-rich features; blocky, prismatic, and dendritic morphologies. XRD results showed the formation of Co3W9C4 phase. The evolution of microstructure has been discussed.

Automated summary

In this study, the impact of atypical WC-Co composite powder on L-PBF process was examined. The results revealed the influence of powder thickness on macro-sized solidification cracks and pores, and discussed the evolution of microstructure.