Cemented carbide, also known as hard alloy, is a composite material made of a carbide phase (usually tungsten carbide) bonded with a metallic binder phase (usually cobalt or nickel). Because of its high hardness, strength, and resistance to wear, cemented carbide is widely used in many different industries. Its composition and application allow for its classification into various categories. Here are some common classifications of cemented carbide:
- Grades based on WC-Co Composition
- ISO Standard Grades: Cemented carbide grades are classified based on the ISO standard, specifying the tungsten carbide (WC) percentage and the binder phase (Co) content. For example, grades like ISO K10, K20, K30, etc., represent different WC-Co compositions.
- Fine-Grain Grades: These grades are appropriate for applications needing high wear resistance and toughness because of their fine-grain size. They typically have higher cobalt content to enhance toughness.
- Ultrafine-Grain Grades: These grades have an even finer grain size than the fine-grain grades, resulting in improved hardness and wear resistance. They are suitable for applications that demand high hardness and wear resistance, such as cutting tools.
- Grades based on Binder Phase
- Cobalt-Bonded Grades: Cemented carbides with cobalt as the primary binder phase are widely used due to their good combination of hardness and toughness. They can be used for many different things, such as mining tools, wear parts, and cutting tools.
- Nickel-Bonded Grades: Improved corrosion resistance is provided by cemented carbides containing nickel as the binder phase, which are frequently utilized in applications requiring resistance to chemical environments.
- Specialty Grades
- Gradient Grades: These grades have graded composition, with varying WC and binder phase content throughout the material. Gradient grades provide enhanced properties, such as improved wear resistance near the surface combined with high toughness in the core. They are used in demanding applications, such as machining and metal forming.
- Coating Grades: Cemented carbide grades are designed for coating applications such as titanium nitride (TiN) or titanium carbonitride (TiCN). Coate has specific compositions and structures to ensure excellent adhesion of the coating material grades, offer improved wear resistance, and extend tool life.
These are some general classifications of cemented carbide based on composition and application. The choice of grade depends on the application’s specific requirements, such as hardness, toughness, wear resistance, and chemical resistance.