1.7709, AFNOR 20CDV5.7, 21CrMoV5.7
Standard reference:
EUROPE EN 10269: 2003
ITALY (UN1 7845-78)
GERMANY (DIN 17200-86) / DIN 17240
FRANCE (NF A 35-552-86)
UK (BS 970 pt.3-96)
USA ASTM A 29
AD 2000 W7
Chemical Analysis (Mass-%)
| Element | C | Si | Mn | P | S | Cr | NI | Mo | V | Al |
| min. | 0.17 | 0.15 | 0.4 | – | – | 1.2 | – | 0.65 | 0.25 | – |
| Max. | 0.25 | 0.35 | 0.8 | 0.025 | 0.03 | 1.5 | 0.6 | 0.8 | 0.35 | 0.03 |
Mechanical Properties according to DIN EN 10269
| Condition | Diameter (mm) | Yield Strength (N/mm²) | Tensile Strength (N/mm²) | Reduction of Area (%) | Elongation (%) | Impact Energy J Charpy-V |
| Quenched (+QT) | ≤160 | ≥550 | 700-850 | ≥60 | ≥16 | ≥63 |
Minimum values of 0.2%yield strength at elevated temperatures
| Condition | Diameter(mm) | Temperature(℃) | Yield Strength (N/mm²) |
| +QT | ≤160 | 300 | ≥460 |
| 500 | ≥350 |
Heat Treatment Reference Values
| Condition | Temperature [℃] | Cooling Medium |
| Quenched (+QT) | 880-950(Hardening) | Air,Oil,Polymer,Water |
| 680-720 (Tempering),min 2h | Air |
Properties
1.7709 is a Cr-Mo-V alloyed heat-resistant structural steel with good toughness. In continuous operation, its application temperature is up to 550°C.
Delivery Condition
– Quenched and tempered (+QT)
– Quenched and tempered, and stress-relieved (+QT +SR)
– Annealed (+AC), max. 229 HBW
Application Area
Components for elevated ambient temperatures up to 550°C.
Application Examples
– Connecting elements
– Turbine shafts
– Flanges and rings
– Components for thermal power plants
