What Is Cemented Carbide

Cemented carbide is made of one or more refractory metal carbides (such as tungsten carbide WC) as the hard phase, with metal binders cobalt (Co), nickel (Ni), iron (Fe) as the binder phase , an alloy composite material with high hardness, high wear resistance and high compressive strength sintered by powder metallurgy method.

Performance characteristics: high hardness, high wear resistance; high compressive strength (up to 6000MPa); good stability; greater brittleness. Compared with tool steel, cemented carbide can increase tool life, increase cutting speed and labor efficiency, and improve the accuracy and finish of the workpiece. Even at a temperature of 500 °C, it remains basically unchanged, and there is still a high hardness at 1000 °C.

Carbide is widely used as tool material, such as turning tools, milling cutters, planers, drills, boring tools, etc., for cutting cast iron, non-ferrous metals, plastics, chemical fibers, graphite, glass, stone and ordinary steel, and can also be used for cutting Difficult-to-machine materials such as heat-resistant steel, stainless steel, high manganese steel, and tool steel.

Cemented carbide has high hardness, strength, wear resistance and corrosion resistance, and is known as "industrial teeth". It is used to manufacture cutting tools, cutting tools, cobalt tools and wear-resistant parts, and is widely used in military industry, aerospace and aviation. , machining, metallurgy, oil drilling, mining tools, electronic communications, construction and other fields, with the development of downstream industries, the market demand for cemented carbide continues to increase. And in the future, the manufacture of high-tech weapons and equipment, the advancement of cutting-edge science and technology, and the rapid development of nuclear energy will greatly increase the demand for high-tech and high-quality and stable carbide products.

Carbide features:

1. High hardness (86～93HRA, equivalent to 69～81HRC);

2. Good thermal hardness (up to 900～1000℃, keep 60HRC);

3. Good wear resistance.

4. The cutting speed of cemented carbide tools is 4 to 7 times higher than that of high-speed steel, and the tool life is 5 to 80 times higher. Manufacturing molds and measuring tools, the service life is 20 to 150 times higher than that of alloy tool steel. It can cut hard materials of about 50HRC.

However, cemented carbide is brittle and cannot be machined. It is difficult to make integral tools with complex shapes. Therefore, blades of different shapes are often made, which are installed on the tool body or mold body by welding, bonding, mechanical clamping, etc. .

Cemented carbide classification:

① Tungsten and cobalt carbide

The main components are tungsten carbide (WC) and binder cobalt (Co).

Its grade is composed of "YG" ("hard and cobalt" in Chinese Pinyin) and the percentage of average cobalt content.

②Tungsten-titanium-cobalt carbide

The main components are tungsten carbide, titanium carbide (TiC) and cobalt. Its grade is composed of "YT" ("hard, titanium" two characters in Chinese Pinyin prefix) and the average content of titanium carbide.

③ Tungsten-titanium-tantalum (niobium) cemented carbide

The main components are tungsten carbide, titanium carbide, tantalum carbide (or niobium carbide) and cobalt. This kind of cemented carbide is also called general cemented carbide or universal cemented carbide. The production of cemented carbide is to mix tungsten carbide and cobalt in a certain proportion, pressurize them into various shapes, and then semi-sinter. This sintering process is usually carried out in a vacuum furnace. It is placed in a vacuum furnace to complete the sintering, and the temperature at this time is about 1300 to 1500 degrees Celsius.

Cemented carbide sintering molding is to press the powder into a billet, and then enter the sintering furnace to heat to a certain temperature (sintering temperature), keep it for a certain time (holding time), and then cool it down to obtain a cemented carbide material with the required properties.

Summarize:

Cemented carbide is made of one or more refractory metal carbides as the hard phase and metal binders Fe, Co, Ni as the binder phase, and is sintered by powder metallurgy. Composite materials with high abrasiveness and high compressive strength;

Cemented carbide production process: four processes of mixing, milling, pressing and sintering.

The final properties of the products obtained from different sintering curves are very different. Different Co content materials have different use ranges: the higher the Co content, the higher the bending strength, but the lower the wear resistance, such as: Co%: 9%, the use of drill bits below 0.15, in order to ensure that customers will not stop cutting; 44 Material, Co%: 6%, used for drills above 1.0 to ensure wear resistance.

The conventional inspection methods of cemented carbide are: density, cobalt magnetism, coercive force, hardness, bending strength, metallographic microscopic analysis (metallographic, scanning electron microscope, energy spectrometer)