High Speed Steel HSS :-
HSS removes metal at a much higher rate or speed than ordinary carbon Steel.
HSS are categorized by being heat treatable to very high hardness (64 HRC) and of retaining their hardness and cutting ability at temp. as high as 540 deg Celsius. Thus permitting truly high speed machining.
Above 540 deg c. they rapidly soften and loose their cutting ability.
Properties of HSS:
1. Excellent red hardness.
2. Good wear resistance.
3. Good Shock resistance
4. Fair machinability
5. Good non-deforming properties.
6. Poor resistance to decarbonization.
Types of HSS Tools :
1. Tungsten base.
2. Molybdenum base.
Both types have similar important properties but as compared to tungsten, Molydenum being adequete and cheap is used more commonly.
Beside tungsten and molybdenum as the primary heat resistant additive there are other elements also present in HSS ;
- Carbon C – for high hardness.
- Chromium Cr – for ease of heat treating.
- V – Vanadium for grain growth, Grain refining and in amounts over 1 % used for abrasion resistance.
- Cobalt Co – Sometimes Cobalt for HSS resistence to heat softening and additional hardness.
Read More : Cutting-tools-in-CNC-Machining
