1.2312+QT - 40CrMnMoS8-6+QT - 19 520+S+QT
Round bars:
+QT – quenched and tempered
+NT – normalized and tempered
Sheets and plates:
+QT – quenched and tempered
+NT – normalized and tempered
⚙️ Basic designation
Steel number: 1.2312
DIN designation: 40CrMnMoS8-6
EN ISO designation: 40CrMnMoS8-6 (EN ISO 4957)
AISI / SAE equivalent: approx. P20+S
Delivery condition: +QT = quenched and tempered
Steel type: Mould steel – pre-hardened, with added sulphur for improved machinability
🔩 Properties
| Property | Description / Value |
|---|---|
| Machinability | Good |
| Polishability | Good |
| Toughness | High |
| Wear resistance | Increased due to sulphur content |
| Hardenability | Very good |
Mechanical properties:
| Property | Value |
|---|---|
| Tensile strength Rm | 1100 – 1250 MPa |
| Yield strength Re | 1000 – 1150 MPa |
| Elongation A5 | 8 – 12 % |
| Hardness after QT | 520 – 600 HB |
🧰 Applications
Mainly used for the production of moulds, tools and components exposed to high mechanical stress. It is particularly suitable for medium-sized to large tools where good machinability, toughness and increased wear resistance are required.
🧪 Chemical composition
| Element | Content (%) |
|---|---|
| C | 0.36 – 0.44 |
| Mn | 0.50 – 0.80 |
| Cr | 1.30 – 1.60 |
| Mo | 0.15 – 0.30 |
| S | 0.08 – 0.13 |
| P | ≤ 0.035 |
| Si | 0.20 – 0.40 |
🔥 Typical heat treatment
| Process | Temperature (°C) | Medium / Procedure | Result / Purpose |
|---|---|---|---|
| Soft annealing | 710 – 740 | Slow cooling in the furnace, approx. 10 °C/h | Hardness approx. 220 HB, improved machinability |
| Hardening | 840 – 870 | Oil or air | Hardness after hardening approx. 50–54 HRC |
| Tempering | 550 – 680 | Air, 2–3 h depending on thickness | Hardness after tempering 280–325 HB, approx. 30–35 HRC |
| Nitriding optional | 500 – 530 | — | Surface hardness up to 900–1000 HV, higher wear resistance |
| Delivery condition +QT | — | Heat-treated – quenched and tempered | Ready for immediate use without further treatment |
