|Strength class||Hardness (HV)||Strength class|
|14H||140||4.6, 4.8, 5.6, 5.8|
|22H||220||6.6, 6.8, 6.9, 8.8|
The division of special steels, due to the working conditions:
- Resistant to corrosion,
- For operation at a reduced temperature,
- For operation at elevated temperature,
- Heat-resistant and heat resistant.
- Resistant to wear.
- With special magnetic properties,
- Highly hardenable – “maraging steel”.
21CrMoV5-7 – alloy steel for operation at elevated temperature – belonging to the heat-resistant and high-temperature creep resistant group. The advantage of this steel is resistance to hot gases and fumes, while maintaining good mechanical properties. It is used for small elements, such as nut bolts, struts, and, moreover, shafts and discs of steam turbines operating at temperatures up to 500°C.