What is the tungsten carbide and its features?

About cemented carbide

Cemented carbide is a kind of very hard and wear resistant material produced with powder metal process, it is normally referred to as hard metal in Europe. Cemented carbide consists of hard phase (such as WC, TiC, TaC, VC and Cr3Cr2) and metal binding phase (such as Co, Ni and Fe, etc.). It combines the high hardness and good wear resistance of carbide phase and sufficient mechanical property and heat shock resistance of metal binding phase and has been widely used in many aspects.

Main specifications of carbide products

1. Hardness: Normally, HRA and HV are used to indicate the hardness, but HRA is more commonly used. For WC-Co carbides, the hardness increases relatively as the cobalt content decreases and WC grain size reduces.

2. Strength: Cemented carbide is in the category of brittle materials. Its strength is normally evaluated by bending strength, compressive strength and fracture toughness, etc. and the simplest and most commonly used method is check its bending strength. In China, bending strength is obtained via 3-point bending test according to GB/T 3851 standard. Bending strength normally increases as the increase of the cobalt content, but after the cobalt content exceeds 15%, bending strength starts to decrease.

3. Density: Density is a reflection of the grade composition, and is an important factor to be controlled in production process. Redundant of insufficient carbon content can all be reflected by density. Carbide density decreases as the cobalt content increases, but it has nothing to do with WC grain sizes.

4. Magnetism: Cobalt is magnetic material and its rule of magnetization complies with magnetization curve of ferromagnetic materials. Therefore, tungsten carbide possesses magnetism. Magnetic property can reflect structural and compositional of carbide and so, it is also an important factor to be controlled in production process.

5. Porosity: Porosity indicates there are micro bores in carbide's microstructure of smooth surface. Micro bores in carbide product is very detrimental to its strength, and the pores are the origin of carbide destruction. The most effective way to eliminate and inhibit pores in carbide is to use sinter-HIP or HIP (hot iso-static press) Process.