Cemented carbide, also known as tungsten steel, is a composite material crafted through powder metallurgy processes. It features high-melting-point metal carbides—primarily tungsten carbide (WC)—as the hard phase, while transition metals such as cobalt (Co), nickel (Ni), or iron (Fe), along with their alloys, serve as the binding phase. Since its invention in the 1920s, cemented carbide has become indispensable in modern industry due to its exceptional hardness, superior wear resistance, "red hardness" (the ability to retain high hardness at elevated temperatures), and remarkable chemical stability—qualities far surpassing those of high-speed steel. Often referred to as the "teeth of industry," it plays an irreplaceable and critical role across a wide range of applications, including metal cutting tools and blades, geological and mining equipment like drill bits and pick teeth, mold manufacturing for processes such as drawing and stamping dies, as well as wear-resistant components and structural parts essential to various key industries.

The exceptional performance of cemented carbides fundamentally stems from their unique "steel-like" composite structure: finely dispersed, ultra-hard WC grains form the material's skeletal framework, bearing the primary load during cutting and wear resistance. Meanwhile, a ductile and tough metallic binder phase firmly holds these hard grains together, not only imparting the necessary strength and toughness to the material but also enabling it to relieve stress concentrations through plastic deformation under load—thereby preventing crack initiation and propagation. This ingenious combination of hard and tough phases achieves an optimal balance between hardness and toughness—a feat that is difficult to attain with a single-material approach.

In this composite system, tungsten carbide (WC) is undoubtedly the decisive factor. The performance of WC encompasses not only its intrinsic physicochemical properties but, more critically, its processability as a raw powder—specifically, parameters such as particle size, shape, distribution, chemical composition (particularly carbon content), purity, and internal microstructural defects. These seemingly minor raw material characteristics are significantly amplified during the complex series of physicochemical processes—including batching, mixing, pressing, and sintering—ultimately influencing, directly or indirectly, the microstructural organization of the cemented carbide (e.g., the final size and morphology of WC grains, the thickness and uniformity of the binder phase, the presence of any tertiary brittle phases or graphite inclusions, and porosity levels). As a result, these factors determine the alloy's macroscopic properties, including mechanical attributes like hardness, wear resistance, strength, and toughness, as well as physical properties such as density, magnetic behavior, and thermal conductivity—and even its chemical performance, such as oxidation resistance and corrosion resistance.

Therefore, a thorough understanding of the various performance indicators of WC, clearly defining the specific requirements these indicators place on cemented carbide production, and systematically investigating how changes in these indicators influence the final alloy properties—as well as uncovering the underlying metallurgical and materials-science mechanisms—is of paramount theoretical value and practical significance. This knowledge is essential for guiding the production of high-quality WC raw powder, optimizing the compositional design and process control of cemented carbides, and enabling the development of new, high-performance carbide materials. This paper will address this central issue by providing a systematic, comprehensive, and in-depth analysis, drawing upon existing research findings.

1. Characteristics of WC and Key Performance Requirements & Evaluation of Cemented Carbides
Tungsten carbide (WC) is a metal-ceramic compound composed of tungsten and carbon, featuring a hexagonal crystal structure (α-WC). Its most remarkable property is its exceptional hardness, with a microhardness reaching 2200–2500 HV—second only to diamond and cubic boron nitride—making it an ideal material for wear resistance. Additionally, WC boasts an extremely high melting point (around 2870°C), a remarkably high elastic modulus (approximately 700 GPa), excellent electrical and thermal conductivity, and outstanding chemical stability, demonstrating superb corrosion resistance even in acidic or alkaline environments. These intrinsic characteristics lay the foundation for WC as the core structural backbone of cemented carbides. However, for cemented carbide manufacturers, the processing performance of WC raw powder is far more critical than its inherent properties. Practical production experience—and extensive research—have shown that the final performance of cemented carbides heavily depends on four key indicators of the WC powder: grain size, carbon content, purity, and the presence of internal defects.

1.1 Requirements for Carbide Alloy Regarding WC Grain Size and Its Distribution

The particle size of WC powder (typically referring to its grain size; the industry also uses FSSS particle size characterization, though it is not listed here, as there currently isn’t a unified standard) and its distribution are among the most critical factors influencing the performance of cemented carbides. Not only does it directly determine the grain size of the hard phase within the alloy, but it also profoundly affects the kinetics of the sintering process, as well as the final microstructure and mechanical properties.

1.1.1 Granularity-Level Division and Application Orientation
Based on the average particle size of WC powder, it is classified into different grades in industry to suit hard alloy products with varying performance requirements—though, in reality, powder manufacturers don’t necessarily follow this classification system.

1.1.2 Requirements for Particle Size Distribution