Hiroshima University researchers successfully 3D print ultra-hard tungsten carbide

Researchers at Hiroshima University have achieved a significant breakthrough in manufacturing by developing a novel 3D printing method for tungsten carbide-cobalt (WC-Co), a material prized for its extreme hardness that rivals sapphire and diamond. The team's work, published in the International Journal of Refractory Metals and Hard Materials, addresses a longstanding challenge in the industry: how to shape this ultra-hard material without the excessive waste and cost associated with traditional powder metallurgy techniques.

The challenge of working with cemented carbides

Cemented carbides like tungsten carbide-cobalt are essential in manufacturing cutting tools, drill bits, and wear-resistant components. Their exceptional hardness makes them ideal for demanding industrial applications, but this same property creates significant manufacturing challenges. Traditional methods require extensive machining and material removal, leading to substantial waste of expensive raw materials like tungsten and cobalt.

"Cemented carbides are extremely hard materials... but they are made from very expensive raw materials such as tungsten and cobalt, making reduction of material usage highly desirable," explains Assistant Professor Keita Marumoto, corresponding author of the study. "By using additive manufacturing, cemented carbide can be deposited only where it is needed, thereby reducing material consumption."

Hot-wire laser irradiation: A new approach

The Hiroshima University team developed a technique called hot-wire laser irradiation that represents a departure from conventional additive manufacturing. Rather than fully melting the feedstock material, this method combines a laser beam with a preheated filler wire to merely soften the metals. This controlled approach helps maintain the material's microstructure and properties while enabling precise deposition.

The researchers experimented with two fabrication orientations: rod-leading and laser-leading. Initial attempts encountered problems with defects and material decomposition, which are common issues when working with such hard materials at high temperatures. The breakthrough came through the introduction of a nickel alloy-based middle layer and precise temperature control.

Achieving defect-free results

The key to success was maintaining temperatures above cobalt's melting point while staying below the threshold where grain growth occurs. This delicate balance preserved the material's microstructure while allowing proper bonding and deposition. The result was a defect-free tungsten carbide-cobalt material with a hardness exceeding 1,400 HV (Vickers hardness), matching the performance of conventionally manufactured carbides.

This achievement is particularly noteworthy because it demonstrates that additive manufacturing can produce WC-Co components with properties equivalent to traditional methods while offering the design flexibility and material efficiency advantages of 3D printing.

Implications for manufacturing

The potential impact of this technology extends throughout the manufacturing sector. Cutting tools, which represent a major application for tungsten carbide-cobalt, could be produced with complex geometries that are difficult or impossible to achieve with conventional machining. The ability to deposit material only where needed could dramatically reduce waste and lower production costs.

Additionally, the technology could enable rapid prototyping and customization of tooling, allowing manufacturers to quickly adapt to changing production requirements. The reduced material waste also aligns with growing sustainability concerns in manufacturing.

Next steps and challenges

While the initial results are promising, the research team acknowledges that further work is needed before the technology can be widely adopted. The current focus is on refining the process to prevent cracking and enable the fabrication of increasingly complex shapes. These improvements will be crucial for expanding the range of applications and ensuring consistent quality across different part geometries.

The development also raises questions about scalability and economic viability for mass production. While 3D printing offers advantages for complex parts and low-volume production, traditional methods may still be more cost-effective for simple, high-volume components.

The future of hard material manufacturing

This research represents an important step toward more sustainable and flexible manufacturing of ultra-hard materials. As the technology matures, it could transform how industries approach the production of cutting tools, wear-resistant components, and other applications requiring extreme hardness.

The work at Hiroshima University demonstrates how innovative approaches to additive manufacturing can overcome longstanding material science challenges. By combining precise temperature control with novel deposition techniques, the team has opened new possibilities for working with some of the hardest materials known to industry.

For manufacturers dealing with the high costs and waste associated with tungsten carbide-cobalt, this development offers a promising path forward. As the technology continues to evolve, it may well revolutionize how cutting tools and other hard material components are designed and manufactured, bringing together the best of both worlds: the extreme performance of cemented carbides with the flexibility and efficiency of additive manufacturing.