Tungsten carbide-cobalt (WC-Co) is widely valued for its extreme hardness, but that same strength also makes it very difficult to shape and manufacture. Current production methods consume large amounts of costly material while delivering relatively modest yields. As a result, researchers have been searching for a more efficient and economical way to produce these exceptionally tough materials.
WC-Co cemented carbides are essential for applications that demand strong resistance to wear and high hardness, including cutting and construction tools. Traditionally, these materials are produced through powder metallurgy. In this process, powders of WC and Co are compressed under high pressure and heated in sintering machines to form solid cemented carbide. While this method produces very durable final products, it uses significant quantities of expensive raw materials and generates inefficient yields.
To address this issue, researchers explored a different approach using additive manufacturing (AM, also commonly known as 3D printing). Their work also incorporates a technique called hot-wire laser irradiation. Together, these methods aim to create cemented carbides that retain their strength and durability while reducing both material waste and production costs.
The findings were published in the International Journal of Refractory Metals and Hard Materials and are scheduled to appear in the journal’s April 2026 print issue.
Laser-Based Additive Manufacturing Approach
The study examined additive manufacturing using hot-wire laser irradiation and tested two different fabrication strategies. Hot-wire laser irradiation (also called laser hot-wire welding) combines a laser beam with a heated filler wire. This pairing increases the deposition rate (how much filler metal is added) and improves overall manufacturing efficiency.
In one of the experimental approaches, the cemented carbide rod leads the direction of fabrication while the laser directly irradiates the top of the rod. In the second approach, the laser leads the process and directs energy between the bottom of the cemented carbide rod and the base material (iron). In both techniques, the materials are softened during fabrication rather than fully melted to form the cemented carbide structure.
“Cemented carbides are extremely hard materials used for cutting tool edges and similar applications, but they are made from very expensive raw materials such as tungsten and cobalt, making reduction of material usage highly desirable. By using additive manufacturing, cemented carbide can be deposited only where it is needed, thereby reducing material consumption,” said corresponding author Keita Marumoto, assistant professor at Hiroshima University’s Graduate School of Advanced Science and Engineering.
Achieving Defect-Free Industrial Hardness
The experiments showed that this additive manufacturing strategy can preserve the hardness and mechanical strength typically achieved through conventional manufacturing methods. The resulting material reached hardness levels above 1400 HV (a unit representing resistance to penetration) while avoiding defects or material breakdown.
Materials with this level of hardness are among the toughest used in industrial applications and rank just below superhard materials such as sapphire and diamond. Producing cemented carbide molds without defects appears achievable with this approach, which was the primary objective of the research. However, the results varied depending on the fabrication method used.
For instance, the rod-leading technique led to decomposition of WC near the top portion of the build, which created defects in the finished material. The laser-leading method also struggled to maintain the hardness required for success.
Researchers addressed these issues by introducing a nickel alloy-based intermediate layer. Combined with careful control of temperature conditions (above the melting point for cobalt, below the temperature of grain growth), this adjustment enabled the production of cemented carbide using additive manufacturing while preserving the material’s hardness.
Future Improvements and Applications
The results provide a promising starting point for further development. Future work will focus on reducing cracking during fabrication and enabling the creation of more complex shapes.
“The approach of forming metal materials by softening them rather than fully melting them is novel, and it has the potential to be applied not only to cemented carbides, which were the focus of this study, but also to other materials,” said Marumoto.
Looking ahead, researchers aim to fabricate cutting tools, investigate the use of other materials, and continue studying ways to improve the durability of parts made with this technique.
Keita Marumoto and Motomichi Yamamoto of the Graduate School of Advanced Science and Engineering at Hiroshima University and Takashi Abe, Keigo Nagamori, Hiroshi Ichikawa and Akio Nishiyama of the Mitsubishi Materials Hardmetal Corporation contributed to this research.