Researchers at Hiroshima U have developed a method to 3D print tungsten carbide–cobalt (WC–Co) cemented carbides, ultra-hard materials typically used in construction and cutting tools. The approach aims to reduce the cost and material waste associated with conventional manufacturing, which involves pressing powders under high pressure and heating them in large furnaces.
Additive Manufacturing Process
The study, led by Keita Marumoto, an assistant professor at the Graduate School of Advanced Science and Engineering, utilized additive manufacturing and a hot-wire laser irradiation method. This technique combines a laser beam with a preheated filler wire to increase process efficiency and the deposition rate of the filler metal.
According to Marumoto, using additive manufacturing allows cemented carbide to be deposited only where it is needed, which is highly desirable because the raw materials, such as cobalt and tungsten, are very expensive. The researchers focused on a novel approach of forming metal materials by softening them instead of fully melting them.
Performance and Results
The team achieved a base material with a hardness of over 1400 HV, a unit representing resistance to penetration. This level of hardness ranks among the toughest industrial materials, positioned just below superhard substances like diamond and sapphire.
The results indicated that the method could maintain the mechanical integrity and hardness of conventionally manufactured WC-Co cemented carbides without introducing decomposition or defects. Microscope studies further revealed that the carbide grains remained small and the structure stayed close to the original rod, with only slight movement of the cobalt binder.
However, the researchers noted some variations in results. The rod-leading method appeared to cause defects in the final product due to the decomposition of WC on the upper part of the build, and the laser leading method faced issues maintaining the necessary hardness for success.
The study was published online in December 2025 in the International Journal of Refractory Metals and Hard Materials and is scheduled for the journal’s April 2026 print issue. Marumoto stated that the approach has the potential to be applied to materials beyond cemented carbides. Future research priorities include fabricating cutting tools, investigating durability improvements, and exploring other materials.
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