Typical Cemented Carbide Tool Materials

Adding TaC (NbC) to cemented carbide is an effective method to enhance its performance. In TiC/Ni/Mo alloys, replacing part of the TiC with carbides like WC and TaC, which offer better toughness, improves the cemented carbide's performance and expands its application range. The addition of WC and TaC enhances:

    ●　Toughness
    ●　Elastic modulus
    ●　Resistance to plastic deformation
    ●　High-temperature strength

It also improves thermal conductivity and thermal shock resistance, making the tool more suitable for interrupted cutting.In WC-Co alloys, performance can be improved by adding 0.5% to 3% (mass fraction) of carbides such as TaC, NbC, Cr3C2, VC, TiC, or HfC. The main objectives include:

    ●　Grain refinement
    ●　Maintaining a uniform crystal structure without significant recrystallization
    ●　Increasing hardness and wear resistance without compromising toughness

Additionally, these additives enhance:

    ●　High-temperature hardness
    ●　High-temperature strength
    ●　Oxidation resistance

During cutting, a tough, self-compensating oxide film forms, which resists adhesive and diffusive wear when machining certain metals or alloys. This improves the tool's wear resistance and increases its ability to resist crater wear and flank wear. These benefits become more pronounced as the cobalt content in the cemented carbide increases.

    ●　Cemented carbide with 1% to 3% (mass fraction) TaC (NbC) can machine various cast irons, including extra-hard cast iron and alloy cast iron.
    ●　Low-cobalt alloys with 3% to 10% (mass fraction) TaC (NbC), such as YG6A, YG8N, and YG813, are versatile. They can process:

Chilled cast iron
Ductile cast iron
Non-ferrous metals
Difficult-to-machine materials like stainless steel, hardened steel, and high-temperature alloys

These are commonly known as general-purpose alloys (YW).Increasing the cobalt content appropriately boosts the strength and toughness of this type of cemented carbide, making it suitable for rough machining and interrupted cutting of difficult-to-machine materials. Applications include:

    ●　Skinning large steel castings and forgings
    ●　Turning, planing, and milling of austenitic steel and heat-resistant alloys
    ●　Machining with large rake angles, large cutting sections, and medium to low speeds
    ●　Rough turning on automatic, semi-automatic, and multi-tool lathes
    ●　Manufacturing drills, gear hobs, and other tools with high cutting edge strength**

In WC-TiC-Co alloys, excessive TiC content increases sensitivity to thermal cracking, leading to greater brittleness. Adding TaC to low-TiC, high-cobalt WC-Ti-Co alloys improves:

    ●　Toughness
    ●　Heat resistance
    ●　Oxidation resistance

While TiC reduces thermal shock resistance, TaC compensates for this, making the alloy suitable for milling operations.Less expensive alternatives like NbC or Hf-Nb carbides (mass fraction: Hf-60%, Nb-40%) can substitute for TaC. In TiC-Ni-Mo alloys, adding TiN, WC, and TaC simultaneously significantly enhances:

    ●　Hardness
    ●　Flexural strength
    ●　Oxidation resistance
    ●　Thermal conductivity

at high temperatures (900–1000°C).