Is Cemented Carbide Tungsten Steel?

Many people think that cemented carbide is tungsten steel, but in fact, cemented carbide is not tungsten steel. Although tungsten steel is a type of cemented carbide, the two are not the same. The tungsten content of cemented carbide is usually above 80%, and its composition and performance characteristics are more extensive. Therefore, although all alloys with a hardness exceeding HRC65 can be called cemented carbide, cemented carbide is not limited to tungsten steel.

Cemented carbide is made of hard compounds of refractory metals and bonding metals through powder metallurgy. It is an alloy material with extremely high hardness. Tungsten carbide (WC) is the main component of cemented carbide, accounting for 70%~97% of the total composition; bonding metal is used to play a bonding role in the alloy, and the content is usually 3%~30%. During the sintering process, it can surround the tungsten carbide powder and bond it tightly together, and after cooling, it becomes cemented carbide.

Therefore, commonly used cemented carbides are divided into three categories according to their composition and performance characteristics: tungsten-cobalt, tungsten-titanium-cobalt, and tungsten-titanium-tantalum (niobium) types. The most widely used in production are tungsten-cobalt and tungsten-titanium-cobalt cemented carbides.

1) Tungsten-cobalt cemented carbides

The main components are tungsten carbide (WC) and cobalt. The brand name is represented by the code YG (the Chinese pinyin initials of the words "hard" and "cobalt"), followed by the percentage of the cobalt content. For example, YG6 represents a tungsten-cobalt cemented carbide with a cobalt content of 6% and a tungsten carbide content of 94%.

2) Tungsten-titanium-cobalt cemented carbide

The main components are tungsten carbide (WC), titanium carbide (TiC) and cobalt. The brand name is represented by the code YT (the Chinese pinyin initials of the words "hard" and "titanium"), followed by the percentage of the titanium carbide content. For example, YT15 represents a tungsten-titanium-cobalt cemented carbide with a titanium carbide content of 15%.

3) Tungsten-titanium-tantalum (niobium) cemented carbide

This type of cemented carbide is also called general cemented carbide or universal cemented carbide. Its main components are tungsten carbide (WC), titanium carbide (TiC), tantalum carbide (TaC) or niobium carbide (NbC) and cobalt. The brand name is represented by the code YW (the Chinese pinyin initials of "hard" and "wan") followed by a sequence number.

Commonly used cemented carbide brands and chemical composition:

Note: "X" after the brand name indicates fine-grained alloy, "C" indicates coarse-grained alloy, and no word indicates general-grained alloy.

02 The difference between tungsten steel and cemented carbide

Generally speaking, tungsten steel is made by adding tungsten raw materials to molten steel in a steelmaking process. It is also called high-speed steel or tool steel, and its tungsten content is generally 15%~25%. In addition to the production of high-speed steel by smelting method, there is also powder metallurgy high-speed steel, which avoids the reduction of mechanical properties and heat treatment deformation caused by carbide segregation caused by smelting production.

Cemented carbide is made by sintering tungsten carbide with cobalt or other bonding metals using powder metallurgy technology. Its tungsten content is generally above 80%.

Simply put, all alloys with a hardness exceeding HRC65 can be called cemented carbide, so tungsten steel belongs to cemented carbide; but strictly speaking, cemented carbide is not necessarily tungsten steel.