Of all tool steels, high-speed steel is the most expensive due to its very high content of expensive alloying additives such as tungsten (W), cobalt (Co), and vanadium (V), not including molybdenum (Mo) and chromium (Cr), which are present in relatively high amounts compared to other steels.

Types of high-speed steel:

-High-speed steel SW7M

-High-speed steel SW18

-High-speed steel SK10V

All of the above-mentioned elements, except for cobalt, form carbides distributed in the steel matrix, thanks to which high-speed steel has all the properties mentioned above. Cobalt, which is omitted, prevents grain growth in steel during heat treatment.

Carbon (C) is responsible for high hardness, and its content in high-speed steels ranges from 0.7 to 1.15%. The more carbide-forming alloying additives there are in steel, the more the carbon content must increase proportionally to maintain the amount of carbides at the appropriate level. Tungsten, which forms hard, fine, and evenly distributed carbides with carbon, is responsible for high abrasion resistance and prevents a decrease in steel hardness during operation at high temperatures, known as “red heat.”

Cobalt prevents high-speed steel from overheating during hardening. This increases the amount of carbides in the steel and raises the melting point of the product during operation. Vanadium also increases abrasion resistance and promotes a fine-grained structure of the product. It improves resistance to high temperatures. Chromium improves the hardenability of steel, and molybdenum, which can to some extent replace tungsten, improves abrasion resistance.

High-speed steel is divided into cobalt high-speed steel – cobalt high-speed steel with the addition of vanadium, molybdenum or carbon – and non-cobalt high-speed steel – tungsten high-speed steel, tungsten steel with the addition of molybdenum or carbon – where all types are referred to as ledeburitic high-speed steels.