What is the difference between high speed steel, tool steel and carbide steel?

Tool steel refers to a variety of carbon and alloy steels that are particularly when used for cutting and drilling. The four major alloying elements that form carbides in tool steel are: tungsten, chromium, vanadium and molybdenum. The two materials from which most cutting tools are made are carbide and high speed steel (HSS).

High Speed Steel is a high carbon tool steel, containing lots of tungsten and cobalt and is rich in molybdenum, tungsten and vanadium. It forms a special class of highly alloyed tool steels, combining properties such as high hot hardness and high wear resistance. These properties are possible to be attained due to a special microstructure, composed of a matrix around 65 HRC even in high-temperature in the case of high-speed cutting.

General carbon tool steel remain very high hardness at room temperature after quenching and low temperature tempering, but when the temperature higher than 200 ℃, was a sharp reduction in hardness, when up to 500 ℃ the hardness was similar to its annealing condition before and completely lost the ability of cutting, this limits the carbon tool steel used for cutting tools. However, due to the exist of its red hardness mentioned above, high-speed steel (representative material M2 steel) makes up for the fatal defects of carbon tool steel. HSS is mainly used to manufacture complex thin blade and impact-resistant metal cutting tools, as well as high-temperature bearing and cold extrusion die, such as turning tool, drill bit, hob, machine saw blade and high demand die etc. It is also used to make small, complicated tools.

A Carbide steel is a compound of carbon with another alloy metallic element. Commonly, referred to tungsten carbide, which is a common example of a metal carbide.  Carbide tools enable harder materials to be machined, potentially up to 70+HRC. It has a high red hardness, even at 1000 ℃ it still has a high hardness. Tungsten carbide is extremely hard and abrasion resistance. Most of its major uses including drill bits and cutting tools, sports equipment and the tips of ballpoint pens.

The main difference between them is mainly listed below:

  • The red hardness of high-speed steel is 650℃, but the Carbide steel can reach 800-1000℃.
  • Carbide steel has more high cutting speed and is 4- 7 times higher than high – speed steel.
  • Carbide is much harder, so it has a longer tool life and faster cutting data than conventional high speed steel.
  • HSS tools also cost less than Carbide tools and are often a good solution in high-mix, low-volume applications.
  • HSS doesn’t have the wear resistance and lifespan of carbide, so it tends to be more resilient and less brittle and is the best choice for deep cuts with small tip sizes in harder materials.

Should we use High-Speed Steel replace Carbide steel for our general-purpose tools, like drills or taps? Honestly, that a complex question, There’s no quick answer because there are lots of factors involved: tool size, depth of cutting, required material removal rate, tool life, cycle time and of cost. Each type of component also presents different challenges, including design, size, batch quantity, material type and hardness.

 

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