As a high-quality carbon structural steel, C40 is defined as a non-alloy steel with an average carbon content of about 0.4% as per European standards.C40 steel has high strength and good machinability, medium cold deformation plasticity, but poor in weldability and hardenability.C40 steel is used in normalized or quenched and tempered condition.It is often used to manufacture small cross-section quenched and tempered parts with large load, large normalized parts with small stress, and surface hardened parts with low requirements on core strength and wear-resistant surface.
C40 Steel Application
This grade of steel is used for forged parts where the strength and toughness of the material are appropriate. C40 may be used for the manufacture of forged crankshafts ,couplings, and cold headed parts,along with a range of parts where the properties of heat-treated C40 are suited to the application.
| Cr + Mo + Ni = max 0.63 |
| C | Si | Mn | Ni | P | S | Cr | Mo |
| 0.37 – 0.44 | max 0.4 | 0.5 – 0.8 | max 0.4 | max 0.045 | max 0.045 | max 0.4 | max 0.1 |
Mechanical properties of steel C40 (1.0511)
| Nominal thickness (mm): | to 16 | 16 – 100 | 100 – 250 |
| Rm – Tensile strength (MPa) (+N) | 580 | 550 | 530 |
| Nominal thickness (mm): | 5 – 10 | 10 – 16 | 16 – 40 | 40 – 63 | 63 – 100 |
| Rm – Tensile strength (MPa) (+C) | 700-1000 | 650-980 | 620-920 | 590-840 | 550-820 |
| Nominal thickness(mm): | to 16 | 16 – 100 | 100 – 250 |
| Re – Upper yield strength or Rp0.2 – 0.2% proof strength (MPa) (+N) | 320 | 290 | 260 |
| Nominal thickness(mm): | 5 – 10 | 10 – 16 | 16 – 40 | 40 – 63 | 63 – 100 |
| Rp0.2 0.2% proof strength (MPa) (+C) | 540 | 460 | 365 | 330 | 290 |
| Nominal thickness (mm): | 5 – 10 | 10 – 16 | 16 – 40 | 40 – 63 | 63 – 100 |
| A – Min. elongation at fracture (%) (+C) | 6 | 7 | 8 | 9 | 9 |
| Nominal thickness (mm): | to 16 | 16 – 100 | 100 – 250 |
| A – Min. elongation Lo = 5,65 √ So (%) (+N) | 16 | 17 | 17 |
| Brinell hardness (HBW): (+SH) | 163 – 211 |
Properties of steel C40 (1.0511)
| Weldability: Due to the medium-high carbon content it can be welded with some precautions. Hardenability: Low hardenability; it shows intermediate features between those of steels with medium and those of steels with high carbon content; therefore it is not easy to obtain the required features by quenching in oil and the quenching in water can result in cracking. |
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