High Speed Steel

High Speed Steel, abbreviated HSS and commonly just listed or described as HSS. A hard steel, about 6 times harder than carbon steel, used for metal cutting tools as it remains hard even at dull red temperatures. It normally contains:

  • Tungsten 12 to 18%, Chromium up to 5% and Carbon 0.4 to 0.7%.

Some of the different classifications of HSS are listed below:


Molybdenum based HSS in tungsten-molybdenum series.


M36 is similar to M2, but with 8% cobalt added. The addition of cobalt increases heat resistance. M36 is also known as HSSE or HSS-E.


M42 is a molybdenum-series HSS alloy with an additional 8% cobalt.


HSCo8 or 8% Cobalt or HSCo – this is high speed steel with 8% cobalt – this allows the steel to maintain properties at higher operating temperatures. The hardness is around 63.5 – 65 Rockwell hardness.

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