27MnCr5 Gear Steel Bar
27MCr5 steel is designed for automotive high-end hardenability gear steel and its production process. The chemical composition, metallography, scanning electron microscopy and mechanical properties were analyzed. The results show that the chemical composition of high-end hardenability gear steel is precisely controlled .
The cleanliness of the molten steel is high and the w (O) is 1.0 × 10-5. The hot-rolled microstructure is ferrite and pearlite. The average pearlite layer is 245 nm and the grain size is above 7.5. The hardenability With an average of 1.5 HRC, to meet the requirements of high-end automotive gear steel.
Chemical Composition:
| Element | Min | Max |
|---|---|---|
| Si | 0.1500 | 0.4000 |
| S | 0.0150 | 0.0300 |
| P | - | 0.0200 |
| Ni | - | 0.2500 |
| Mo | - | 0.1000 |
| Mn | 0.8000 | 1.1000 |
| Cr | 1.0000 | 1.3000 |
| C | 0.3300 | 0.4000 |
| B | - | 0.0005 |
| Al | 0.0200 | 0.0500 |
Mechanical Properties:
| Yield Rp0.2 (MPa) | Tensile Rm (MPa) | Impact KV/Ku (J) | Elongation A (%) | Reduction in cross section on fracture Z (%) | As-Heat-Treated Condition | Brinell hardness (HBW) |
|---|---|---|---|---|---|---|
| 366 (≥) | 416 (≥) | 32 | 21 | 34 | Solution and Aging, Annealing, Ausaging, Q+T,etc | 442 |
| Temperature (°C) | Modulus of elasticity (GPa) | Mean coefficient of thermal expansion 10-6/(°C) between 20(°C) and | Thermal conductivity (W/m·°C) | Specific thermal capacity (J/kg·°C) | Specific electrical resistivity (Ω mm²/m) | Density (kg/dm³) | Poisson’s coefficient, ν |
|---|---|---|---|---|---|---|---|
| 11 | - | - | 0.44 | - | |||
| 831 | 489 | - | 24.3 | 343 | - | ||
| 159 | - | 31 | 42.2 | 241 | 413 |