1.1191 | C45E +QW +T Hardened and tempered (quenchant: water)
| Numeric designation | 1.1191 |
|---|---|
| Chemical designation | C45E |
| State | +QW +T Hardened and tempered (quenchant: water) |
| Etching | 3% Nital |
This hypoeutectoid steel (bar stock with ⌀ = 20 mm) with 0.43% carbon (measured by OES) was austenitized at 850 °C for 30 min, quenched in water, and then tempered at 250 °C for 2 hours. The C45E is a shell hardener.
At the edge, the microstructure is completely martensitic, as the critical cooling rate was reached there. Due to the decreasing quenching effect with increasing edge distance, the formation of fine-grained perlite (formerly troostite) in the martensitic matrix starts at a depth of approx. 1 mm. At 2 mm edge distance, ferrite is additionally present on the grain boundaries, partly in Widmannstätten arrangement.
In the core of the specimen the microstructure consists entirely of ferrite and pearlite.
The hardness is about 560 HV5 at the edge of the sample, starts to decrease noticeably at about 2 mm distance from the edge and then decreases further and further towards the core to an average core hardness of 291 HV5.
