Toward cheaper, tougher tool parts 3D printing tungsten carbide-cobalt with less waste

Hiroshima University researchers are working on 3D printing tungsten carbide–cobalt (WC–Co), a super-hard material used in cutting and construction tools. Their hot-wire laser approach uses less of the expensive raw material and still delivers very high hardness, pointing to a more efficient way to make wear-resistant parts.

Tungsten carbide–cobalt (WC–Co) is valued for its exceptional hardness, but that same strength also makes it notoriously difficult to shape. Conventional production methods are costly and material-intensive relative to the usable output, and researchers at Hiroshima University argue that a more economical route to manufacturing is overdue.

WC–Co cemented carbides are widely used wherever high wear resistance and hardness are critical, including cutting and construction tools. Today, they are typically produced via powder metallurgy: WC and Co powders are consolidated under high pressure and then sintered to form the final material. While this approach delivers highly durable, high-hardness components, it consumes substantial amounts of expensive feedstock and often results in suboptimal yield.

The study explores an alternative pathway based on additive manufacturing using a hot-wire laser irradiation method. The goal is to produce WC–Co cemented carbides without compromising hardness or durability, while reducing both material waste and overall manufacturing cost.

The study focuses on the use of AM, specifically hot-wire laser irradiation, along with two fabrication methods for their experiment. Firstly, hot-wire laser irradiation (also called laser hot-wire welding) is a technique in which a laser beam and a preheated filler wire are combined to increase the deposition rate (how much of the filler metal is added) and efficiency of the process.

One fabrication method used in this study involves direct irradiation on top of the cemented carbide rod, with the rod leading the direction of fabrication. The other method is led by the laser and is irradiated by the laser between the bottom of the cemented carbide rod and the base material (iron). In both methods, the metals are softened instead of completely melted to form the cemented carbide.

“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.

Defect-free, industrial-grade carbides achieved

The results showed that the method can preserve the hardness and mechanical integrity of conventionally manufactured WC-Co cemented carbides, producing a base material with a hardness above 1400 HV (a measure of resistance to indentation) without defects or decomposition. At this hardness level, the material ranks among the toughest used in industry, surpassed only by superhard substances such as sapphire and diamond. Overall, defect-free fabrication of cemented carbide molds appears achievable — the central aim of the study — although performance was not fully consistent across all trials.

Some approaches revealed clear limitations. The rod-leading method, for instance, appears to promote WC decomposition in the upper region of the build, which then translates into defects in the final part. The laser-leading method also struggled to retain the hardness required for reliable outcomes. The researchers addressed these issues by introducing a nickel alloy-based intermediate layer and by tightly controlling process temperatures — keeping them above cobalt’s melting point while remaining below the threshold that would trigger grain growth. With these measures, they demonstrated additively manufactured cemented carbide that maintained the targeted hardness.

These findings provide a strong basis for further refinement. Next steps include mitigating cracking and expanding the process window to enable more complex geometries.

“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, the team’s priorities include fabricating cutting tools, testing additional material systems, and systematically improving durability.

Original Article: Effect of the hot-wire laser irradiation method and a Ni-based alloy middle layer on mechanical properties and microstructure in additive manufacturing of WC–Co cemented carbide; International Journal of Refractory Metals and Hard Materials; DOI:10.1016/j.ijrmhm.2025.107624

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