Hiroshima University 3D Prints Tungsten Carbide-Cobalt, One of Earth's Hardest Metals

Tungsten Carbide Is a Manufacturing Nightmare

Tungsten carbide-cobalt is one of the toughest materials used in industry. Cutting tools, drills, mining equipment, and construction bits all rely on it because the material shrugs off wear, pressure, and repeated impacts. The problem is making it. Conventional powder metallurgy presses fine tungsten and cobalt powders together, then sinters them at high temperature. The process works, but it wastes expensive raw material and often delivers low yields from costly inputs.

A team at Hiroshima University has now demonstrated a different approach: additively manufacturing the same cemented carbide using hot-wire laser irradiation. Instead of filling a mold and sintering, the process deposits material only where it is needed, guided by a laser and a preheated filler wire.

How Hot-Wire Laser Deposition Works

The researchers combined a laser beam with a preheated filler wire carrying the WC-Co feedstock. Heating the wire before it reaches the build surface lets the material deposit faster and at lower laser energy than conventional powder bed methods. The team tested two configurations: one where the laser sat on top of the rod being deposited, and another where the laser led the process, irradiating the bond between the fresh material and the base.

Neither approach fully melted the carbide. Partial softening preserved the internal structure that gives tungsten carbide its hardness, while still forming a strong metallurgical bond.

Hardness Without Defects

The resulting parts measured above 1400 HV on the Vickers hardness scale. That puts the printed material among the hardest commonly used industrial materials, below diamond and sapphire but well above most steels. The researchers found no cracks, pores, or decomposition in the printed samples.

"By using additive manufacturing, cemented carbide can be deposited only where it is needed, thereby reducing material consumption," said Keita Marumoto, assistant professor at Hiroshima University's Graduate School of Advanced Science and Engineering. Marumoto co-authored the study with colleagues from Mitsubishi Materials Hardmetal Corporation.

Why This Matters for Tooling

Tungsten and cobalt prices make waste expensive. Cutting tool manufacturers often machine or grind away a large share of a sintered blank to reach the final geometry. If hot-wire laser deposition can deposit carbide only on wear surfaces, the material bill drops significantly. The process also opens the door to repair and remanufacturing of worn carbide tooling, which today usually means scrapping the whole insert.

The study was published in the International Journal of Refractory Metals and Hard Materials. The next step is scaling the deposition rate and testing the printed carbide in real cutting applications.