2 days ago
Tungsten carbide-cobalt (WC-Co) is highly valued for its extreme hardness, but this same strength makes it difficult to shape and manufacture. Current production methods consume large quantities of expensive materials while yielding relatively modest outputs. Consequently, researchers have been seeking a more efficient and cost-effective way to produce these exceptionally tough materials.
WC-Co cemented carbides are critical for applications demanding strong wear resistance and high hardness, such as cutting and construction tools. Traditionally, these materials are produced via powder metallurgy, where WC and Co powders are compressed under high pressure and sintered at elevated temperatures to form solid cemented carbide. Although this method yields very durable products, it requires significant amounts of costly raw materials and results in inefficient yields.
To overcome these challenges, researchers explored additive manufacturing (AM), commonly known as 3D printing, combined with a technique called hot-wire laser irradiation. Together, these methods aim to produce cemented carbides that maintain their strength and durability while reducing material waste and lowering production costs.
The findings were published in the International Journal of Refractory Metals and Hard Materials and are scheduled for the journal's April 2026 print issue.
Laser-Based Additive Manufacturing Approach
The study investigated additive manufacturing using hot-wire laser irradiation and tested two fabrication strategies. Hot-wire laser irradiation, also known as laser hot-wire welding, combines a laser beam with a heated filler wire, increasing the deposition rate and improving manufacturing efficiency.
In one approach, the cemented carbide rod leads the fabrication direction while the laser irradiates the top of the rod. In the second, the laser leads the process, directing energy between the bottom of the cemented carbide rod and the iron base material. In both methods, materials are softened rather than fully melted during fabrication 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," explained Keita Marumoto, assistant professor at Hiroshima University's Graduate School of Advanced Science and Engineering and corresponding author.
Achieving Defect-Free Industrial Hardness
The experiments demonstrated that this additive manufacturing strategy can preserve the hardness and mechanical strength typically achieved through conventional methods. The resulting material reached hardness levels above 1400 HV (a measure of resistance to penetration) while avoiding defects or material breakdown.
Materials with this hardness rank among the toughest used industrially, just below superhard materials like sapphire and diamond. Producing defect-free cemented carbide molds appears achievable with this approach, which was the primary research goal. However, results varied depending on the fabrication method.
For example, the rod-leading technique caused decomposition of WC near the top of the build, creating defects. The laser-leading method also struggled to maintain the required hardness.
Researchers resolved these issues by introducing a nickel alloy-based intermediate layer. Along with careful temperature control—maintaining temperatures above cobalt's melting point but below grain growth thresholds—this adjustment enabled additive manufacturing of cemented carbide while preserving hardness.
Future Improvements and Applications
The results offer a promising foundation 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 rather than fully melting them is novel and has potential applications beyond cemented carbides," said Marumoto.
Looking ahead, researchers plan to fabricate cutting tools, explore other materials, and continue improving the durability of parts made with this technique.
The research team includes Keita Marumoto and Motomichi Yamamoto from Hiroshima University's Graduate School of Advanced Science and Engineering, along with Takashi Abe, Keigo Nagamori, Hiroshi Ichikawa, and Akio Nishiyama from Mitsubishi Materials Hardmetal Corporation.
