We manufacture forging ingots, billets, and blooms in carbon steel specifically for C 40, designed for medium-to-high strength engineering applications where good hardness, toughness, and wear resistance are required.
C 40 is a medium carbon, unalloyed engineering steel that offers higher strength and hardness than C 30 and C 35. With its optimized carbon and manganese content, C 40 is suitable for components subjected to moderate to heavy mechanical loads. It is widely used in automotive, machinery, and general engineering applications where reliable performance is essential.
| Element | Content (%) | Function / effect |
| Carbon © | 0.35 – 0.45 | Provides higher strength, hardness, and wear resistance |
| Manganese (mn) | 0.60 – 0.90 | Improves hardenability, strength, and toughness |
| Sulfur (s) | 0.050 max | Improves machinability; controlled to avoid brittleness |
| Phosphorus (p) | 0.050 max | Aids machinability; limited to maintain toughness |
| Silicon (si) | 0.05 – 0.35 | Acts as deoxidizer and increases strength |
| Chromium (cr) | Nil | Not intentionally added |
| Nickel (ni) | Nil | Not present |
| Molybdenum (mo) | Nil | Not present |
| Other elements | — | No significant alloying additions |
C 40 is the ideal choice when higher strength, hardness, and wear resistance are required without the use of alloying elements. Its excellent response to heat treatment, good machinability, and economical cost make it a preferred material for demanding engineering applications.
| Grade | Carbon (%) | Key applications | Heat treatment | Comments |
| C 40 | 0.35 – 0.45 | Shafts, gears, forgings | Normalizing / q&t | Good strength and wear resistance |
| C 35 | 0.30 – 0.40 | General engineering parts | Normalizing / q&t | Slightly lower strength |
| EN8 | 0.35 – 0.45 | Engineering components | Normalizing | Similar properties |
| Aisi 1040 | 0.37 – 0.44 | Automotive parts | Normalizing / q&t | American equivalent |
| S40c | 0.38 – 0.43 | Machined components | Normalizing | Japanese equivalent |
C 40 is a medium carbon engineering steel that offers a strong combination of strength, toughness, and wear resistance. It is widely used in machined and forged components subjected to moderate to heavy mechanical loads.