3D Printing Tungsten Carbide: How Hot-Wire Laser Technology…

Researchers at Hiroshima University in Japan have achieved what many in the manufacturing world considered near-impossible: successfully 3D printing tungsten carbide–cobalt (WC-Co), one of the hardest engineering materials on Earth. Published in the International Journal of Refractory Metals and Hard Materials (April 2026, Vol. 136), the research introduces a technique called hot-wire laser irradiation that could fundamentally change how ultra-hard cutting tools, industrial molds, and wear-resistant components are made.

What Is Tungsten Carbide–Cobalt (WC-Co)?

Tungsten carbide–cobalt, also known as cemented carbide, is the material behind virtually every cutting tool edge, drill bit, and industrial blade that needs to hold up under extreme wear. It ranks just below superhard materials like sapphire and diamond on the hardness scale, typically achieving 1,400+ HV (Vickers hardness) or higher.

That incredible hardness comes from tungsten carbide (WC) particles held together by a cobalt (Co) binder matrix. The result is a composite that combines extreme wear resistance with enough toughness to survive high-impact industrial applications — from machining steel to drilling through rock and concrete.

But that same hardness makes WC-Co notoriously difficult to manufacture. Traditional production relies on powder metallurgy: tungsten and cobalt powders are compressed under extreme pressure and sintered at high temperatures. This process wastes significant amounts of expensive raw materials and produces relatively modest yields. Tungsten and cobalt are both costly and, in cobalt’s case, subject to supply chain concerns due to mining practices.

Why 3D Printing WC-Co Was So Difficult

The additive manufacturing community has been trying to 3D print tungsten carbide for years. The problem isn’t getting the material hot enough — it’s what happens when you do.

Standard metal 3D printing methods like laser powder bed fusion (LPBF) work by fully melting metal powder and letting it solidify layer by layer. But tungsten carbide doesn’t tolerate that approach well. When WC-Co is fully melted and rapidly cooled, several problems emerge:

• Thermal cracking — The extreme temperature gradients between molten and solid zones cause internal stresses that crack the material
• WC decomposition — Tungsten carbide begins to break down at high temperatures, losing the very microstructure that gives it its hardness
• Cobalt evaporation — The cobalt binder has a lower boiling point than tungsten carbide’s melting point, meaning it can vaporize before the carbide even melts
• Residual porosity — Incomplete fusion leaves voids that weaken the final part

These issues have made WC-Co one of the most challenging materials to adapt to additive manufacturing. Previous attempts using laser powder bed fusion, electron beam melting, and binder jetting all produced parts with cracks, decomposition, or insufficient hardness.

The Breakthrough: Hot-Wire Laser Irradiation

The Hiroshima University team, led by Keita Marumoto (assistant professor at the Graduate School of Advanced Science and Engineering), took a fundamentally different approach. Instead of fully melting the material, they used a technique called hot-wire laser irradiation — sometimes referred to as laser hot-wire welding — that softens the metals just enough to fuse without destroying the microstructure.

Here’s how it works:

1. A filler wire made of WC-Co cemented carbide is fed into the work area
2. The wire is preheated by electrical resistance (the “hot wire” component) before reaching the deposition zone
3. A laser beam provides additional focused energy to soften — not melt — the material at the point of deposition
4. The softened material fuses with the layer below, building up the part gradually

The key innovation is maintaining the material in a semi-solid, softened state rather than a fully liquid melt pool. This approach avoids the thermal shock that causes cracking in conventional laser-based 3D printing while preserving the WC grain structure that gives the material its hardness.

“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.

Two Fabrication Strategies Tested

The researchers tested two different deposition strategies to find the optimal approach:

Strategy 1: Rod-Leading Method

In the rod-leading approach, the cemented carbide rod leads the direction of fabrication. The laser directly irradiates the top of the rod, heating it from above. However, this method had a significant drawback: it caused decomposition of WC near the top portion of the build, creating defects in the finished material. The direct laser exposure was too aggressive for the carbide structure.

Strategy 2: Laser-Leading Method

In the laser-leading approach, the laser leads the process and directs energy between the bottom of the cemented carbide rod and the base material (iron substrate). This provided more controlled heating but initially struggled to maintain the hardness required for industrial applications.

The Solution: Nickel Alloy Intermediate Layer

The breakthrough came when the team introduced a nickel-based alloy intermediate layer between the WC-Co and the substrate. Combined with precise temperature control — keeping the process above cobalt’s melting point but below the temperature where WC grain growth accelerates — this adjustment enabled the production of defect-free cemented carbide that retained its industrial-grade hardness.

The resulting material achieved hardness levels above 1,400 HV, comparable to conventionally manufactured WC-Co cemented carbides. This represents the first time additive manufacturing has produced WC-Co parts with mechanical properties matching traditional powder metallurgy.

Why This Matters for Manufacturing

The implications of this research extend far beyond the laboratory. Here’s why this breakthrough could reshape industrial manufacturing:

Massive Material Savings

“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,” Marumoto explained. “By using additive manufacturing, cemented carbide can be deposited only where it’s needed, thereby reducing material consumption.”

Traditional powder metallurgy wastes significant tungsten and cobalt — both expensive and strategically important materials. Additive manufacturing deposits material only where needed, dramatically reducing waste.

Complex Geometries Become Possible

Current WC-Co manufacturing is limited to shapes achievable through pressing and sintering powder. 3D printing opens the door to complex internal channels, optimized geometries, and conformal cooling features that were previously impossible with cemented carbides.

Repair and Maintenance Applications

Rather than replacing entire cutting tools or wear components, this technology could enable in-situ repair — depositing fresh WC-Co onto worn surfaces to extend tool life. This is particularly valuable for large, expensive industrial tooling.

Supply Chain Resilience

Tungsten and cobalt are both subject to geopolitical supply constraints. Reducing waste through additive manufacturing makes the supply of these critical materials go further — a significant consideration for defense and aerospace applications that depend on cemented carbides.

How It Compares to Traditional Manufacturing

Property	Traditional Powder Metallurgy	Hot-Wire Laser AM
Hardness	1,400–1,600+ HV	1,400+ HV ✅
Material Waste	High	Minimal ✅
Geometry Complexity	Limited	High ✅
Repair Capability	Not possible	Possible ✅
Production Speed	Slow (multi-step)	Moderate
Defect Rate	Low (mature process)	Improving ⚠️
Scalability	Proven at scale	Early stage ⚠️

The Research Team and Collaboration

This breakthrough wasn’t achieved in isolation. The research represents a collaboration between academia and industry:

• Keita Marumoto (corresponding author) and Motomichi Yamamoto — Hiroshima University, Graduate School of Advanced Science and Engineering
• Takashi Abe, Keigo Nagamori, Hiroshi Ichikawa, and Akio Nishiyama — Mitsubishi Materials Hardmetal Corporation

The involvement of Mitsubishi Materials — one of the world’s leading producers of cemented carbide tools — signals that this research has genuine commercial potential. See also: 3D Printing Safety Equipment Guide: Respirators, G…. Industry partnerships like this are critical for translating laboratory breakthroughs into production-ready manufacturing processes.

The paper, “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,” is published in the International Journal of Refractory Metals and Hard Materials, Volume 136 (April 2026), with DOI: 10.1016/j.ijrmhm.2025.107624.

What’s Next?

The researchers have identified several areas for future development:

• Reducing cracking during fabrication — while the Ni-based intermediate layer eliminated many defects, some cracking still occurs during the process
• Enabling more complex shapes — current demonstrations are relatively simple geometries; expanding to intricate tool shapes is a priority
• Fabricating cutting tools — the ultimate goal is producing ready-to-use WC-Co cutting tools directly from additive manufacturing
• Exploring other materials — the softening-instead-of-melting approach may work for other difficult-to-print materials beyond WC-Co

If the team can address cracking and scale the process, the implications are profound. The $25+ billion global cutting tool market could see a shift from centralized powder metallurgy plants to distributed additive manufacturing — the same transformation that Divergent Technologies is bringing to defense manufacturing.

Frequently Asked Questions

Sources: ScienceDaily, Hiroshima University, International Journal of Refractory Metals and Hard Materials (DOI: 10.1016/j.ijrmhm.2025.107624), VoxelMatters, TechSpot, Tom’s Hardware