# An Analysis of the Five Core Properties of Cemented Carbides

As an indispensable advanced material in modern industry, cemented carbide—thanks to its unique compositional design and powder metallurgy processes—demonstrates irreplaceable advantages in cutting tools, die and mold manufacturing, aerospace, and other fields. Its core performance is determined by the synergistic interaction between hard phases such as tungsten carbide (WC) and binder phases like cobalt (Co) and nickel (Ni). The following analysis examines its performance advantages across five key dimensions.

### I. Ultra-Hard and Wear-Resistant: Breaking the Limits of Metallic Materials

The hardness of cemented carbide can reach HRA 86–93, equivalent to HRC 69–81, far exceeding that of high-speed steel (HRC 62–65). This exceptional hardness stems from the nanoscale grain structure of tungsten carbide particles—individual tungsten carbide grains exhibit a microhardness exceeding 1,800 kg/mm², approaching diamond‑level hardness. For instance, in precision bearing manufacturing, cemented carbide balls produced with submicron‑sized WC particles can achieve surface roughness as low as Ra 0.01 μm, meeting the stringent requirements of ultra‑precision machining.

Wear resistance improves markedly with the refinement of WC grain size. Experimental data show that when the grain size is reduced from 5 μm to 0.5 μm, the wear rate decreases by 72%. This property makes it an ideal material for high‑wear applications such as wire‑drawing dies and cold‑heading dies. For example, in automotive connecting‑rod cold‑heading dies, a die made from YG15C cemented carbide (with WC grains of 2–4 μm and a Co content of 15%) can achieve a service life of up to 800,000 cycles—40 times that of conventional tool steels.

### II. Exceptional Red Hardness: Steadfast Performance at High Temperatures

The red hardness (high-temperature hardness retention) of cemented carbides can reach 900–1000°C, which is their key advantage over conventional tool materials. At 800°C, their hardness remains at HRA 77–85, whereas high-speed steel loses more than half its hardness, dropping below HRC 50, by 600°C. This remarkable property stems from tungsten carbide’s exceptionally high melting point (2870°C) and the thermal stability of its cobalt binder.

Its value is particularly evident in aerospace applications. When machining the TC4 titanium alloy, conventional tools soften at just 500°C, whereas carbide tools maintain cutting stability up to 800°C, enabling a threefold increase in cutting speed and a fifteenfold extension of tool life. The WC/WB–WCoB coating exhibits an attrition rate of only 0.002 mm³/N·m at 1,000°C, making it ideally suited for protecting the inner walls of rocket engine nozzles.

### III. Balance Between Compressive Strength and Toughness: A Mechanical Property That Combines Rigidity and Flexibility

The compressive strength of cemented carbide reaches 4,000–6,000 MPa, more than twice that of high-speed steel. This property enables it to excel in heavy‑load stamping dies; for example, when YG20C cemented carbide (with a 20% cobalt content) is used for automotive body panel stamping dies, it can withstand pressures on the order of 2,000 tons without undergoing plastic deformation.

Toughness is regulated by cobalt content. YG8 alloy with a cobalt content of 6%–8% strikes a balance between hardness and toughness, achieving a flexural strength of 2500 MPa and an impact toughness of 3.5 J/cm², enabling it to withstand cutting vibrations while resisting the propagation of microcracks. In oil drilling, the YG11C drill bit—containing 11% cobalt—maintains structural integrity under impact loading, with drilling efficiency 40% higher than that of steel bits.

### IV. Excellent Chemical Stability: Reliable Assurance in Extreme Environments

Cemented carbides exhibit exceptional corrosion resistance at room temperature in dilute acids, alkalis, and salt solutions. At ambient conditions, the WC phase shows a corrosion rate of less than 0.01 mm/year when exposed to hydrochloric and sulfuric acids, while the cobalt binder further enhances this protection by forming a passivation film. In marine engineering, WC–Ni-based cemented carbide valves have demonstrated service lives exceeding 20 years in seawater, significantly surpassing those of stainless steel valves.

High-temperature oxidation resistance is achieved through additive optimization. A cemented carbide containing 1% TaC exhibits an oxidation weight gain in air at 800°C that is only one-third that of a conventional alloy, owing to the dense oxide layer formed by TaC on the surface. In the chemical industry, a cemented carbide stirrer containing Cr3C2 has demonstrated corrosion‑free operation for three consecutive years in concentrated sulfuric acid, whereas a 316L stainless steel stirrer lasts only about six months.

### V. Outstanding Dimensional Stability: The Cornerstone of Precision Manufacturing

The thermal expansion coefficient of cemented carbide is only 4.5–6.0 × 10⁻⁶/K, which is one-third that of steel. This low thermal‑induced dimensional change makes it an ideal core material for precision measuring instruments. For example, when a micrometer’s screw is made from YG6 cemented carbide, its dimensional variation over the temperature range from −20°C to 150°C does not exceed 0.3 μm, thereby meeting the accuracy requirements of 0.001 mm.

In semiconductor manufacturing, wafer‑handling rollers made of WC‑Co cemented carbide achieve roundness errors within 0.5 μm, ensuring vibration‑free transport of 12‑inch wafers. This dimensional stability stems from the isotropic properties of the WC grains and the uniform distribution of the cobalt phase, achieved through precise microstructural control via powder metallurgy.

### Conclusion

From deep-space exploration to nanomanufacturing, the performance advantages of cemented carbides are continually expanding industrial frontiers. With breakthroughs in technologies such as nanocrystalline microstructure control and coherent interface design, modern cemented carbides have achieved a simultaneous enhancement of hardness and toughness—indeed, a novel ultra‑low‑cobalt alloy boasts a hardness of 2143 kgf/mm² and a fracture toughness of 9.7 MPa·m¹/², marking a new stage in materials science. This unique combination of rigidity and ductility, along with exceptional resistance to both extreme cold and heat, will continue to drive manufacturing toward ever greater precision and efficiency.

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