Steel Annealing
Annealing and temper colours
Case hardening and heat treatment
Temperatures for case hardening
The usual temperatures and heat treatments associated with the case hardening of case hardening steels are listed in the following tables.
According to the standard DIN EN 10084, the following temperatures are defined for the case hardening of case hardening steels:
| Steel designation | Carburising temperature 1) | Hardness at | Cooling agent | Tempering 3) | ||
|---|---|---|---|---|---|---|
| Short name | Material number | Core hardness temperature 2) | Surface hardness temperature 2) | |||
| C10E | 1.1121 | 880 … 980°C | 880 … 920°C | 780 … 820°C | With a view to the required component properties, the choice of cooling (quenching) agent depends on: ■ the hardenability or case hardenability of the steel used ■ the shape and cross-section of the workpiece that is to be hardened ■ the effect of the cooling agent | 150 … 200°C |
| C10R | 1.1207 | |||||
| C15E | 1.1141 | |||||
| C15R | 1.1140 | |||||
| 17Cr3 | 1.7016 | 860 … 900°C | ||||
| 17CrS3 | 1.7014 | |||||
| 28Cr4 | 1.7030 | |||||
| 28CrS4 | 1.7036 | |||||
| 16MnCr5 | 1.7131 | |||||
| 16MnCrS5 | 1.7139 | |||||
| 20MnCr5 | 1.7147 | |||||
| 20MnCrS5 | 1.7149 | |||||
| 20MoCr4 | 1.7321 | |||||
| 20MoCrS4 | 1.7323 | |||||
| 20NiCrMo2-2 | 1.6523 | |||||
| 20NiCrMoS2-2 | 1.6526 | |||||
| 17NiCrMo6-4 | 1.6566 | 830 … 870°C | ||||
| 17NiCrMoS6-4 | 1.6569 | |||||
| 20NiCrMoS6-4 | 1.6571 | |||||
1) The criteria that have a crucial influence on the choice of carburising temperature mainly include
the required carburisation time, the chosen carburisation agent, the facility available, the planned process and the required structural state.
Carburisation is normally carried out at less than +950 °C for direct hardening.
In special cases, carburising temperatures in excess of +1000 °C are used.
2) In direct hardening, the material is either quenched at the carburising temperature or at a lower temperature.
Where there is a risk of distortion in particular, the lower hardening temperatures from this range are considered in preference.
3) Tempering duration not less than 1 h (guide value).
Heat treatment during case hardening
The usual heat treatments associated with case hardening correspond to the following processes:
