What is cementd carbide?

Cemented carbide is a kind of refractory carbide (tungsten carbide, titanium carbide, etc.) powder as the main component, adding as a bonding agent of metal powder (cobalt, nickel, etc.), by powder metallurgy and obtained alloy. It is mainly used in the manufacture of high-speed cutting tools and hard and tough material cutting tools, as well as the production of cold working molds, measuring tools and high wear-resistant parts that are not affected by impact and vibration.

▌ Features of cemented carbide

(1) High hardness, wear resistance and red hardness

The hardness of cemented carbide at room temperature can reach 86~93HRA, equivalent to 69~81HRC. At 900~1000℃ can maintain high hardness, and has excellent wear resistance. Compared with high-speed tool steel, the cutting speed can be 4 to 7 times higher, the life is 5 to 80 times longer, and the hard material with a hardness of up to 50HRC can be cut.

(2) High strength and elastic modulus

The compressive strength of cemented carbide is as high as 6000MPa, and the elastic modulus is (4~7) ×105MPa, which is higher than that of high-speed steel. However, its bending strength is low, generally 1000~3000MPa.

(3) Good corrosion resistance and oxidation resistance

Generally, it has good resistance to atmospheric, acid, alkali and other corrosion, and is not easy to oxidize.

(4) The linear expansion coefficient is small

When working, the shape and size are stable.

(5) Formed products are no longer processed and reground

Due to the high hardness and brittleness of cemented carbide, no longer cutting or regrinding after powder metallurgy forming sintering, special reprocessing, can only use electric discharge, wire cutting, electrolytic grinding and other electrical processing or special grinding wheel grinding. A product of a certain specification, usually made of cemented carbide, brazed, bonded, or mechanically clamped to a body or die for use.

▌ Commonly used cemented carbide

Commonly used cemented carbide is divided into three categories according to composition and performance characteristics: tungsten cobalt, tungsten titanium cobalt, tungsten titanium tantalum (niobium). The most widely used in the production of tungsten cobalt and tungsten titanium cobalt cemented carbide.

(1) Tungsten cobalt carbide

The main components are tungsten carbide (WC) and cobalt, and the grade is code-named YG (" hard "and" cobalt "), followed by the percentage value of cobalt content. For example, YG6 means tungsten cobalt carbide with a cobalt content of 6%, and tungsten carbide content of 94%.

(2) Tungsten titanium cobalt carbide

The main components are tungsten carbide (WC), titanium carbide (TiC) and cobalt, and the brand is code-named YT (" hard "and" titanium "), followed by the percentage value of titanium carbide content. For example, YT15 means tungsten titanium cobalt carbide with 15% titanium carbide content.

(3) Tungsten titanium tantalum (niobium) cemented carbide

This kind of carbide is also known as universal carbide or universal carbide, the main components are tungsten carbide (WC), titanium carbide (TiC), tantalum carbide (TaC) or niobium carbide (NbC) and cobalt composition. The grade is indicated by the code YW (" hard "and" Wan "two characters in Chinese pinyin) followed by an ordinal number.

Table① Commonly used cemented carbide grade and chemical composition

Note: After the grade, "X" means fine particle alloy, "C" means coarse particle alloy, and no word is general particle alloy