Applications of Steel Grades – Insights
1. Plain Carbon Steels (Simple. Reliable. Cost-Effective.)
Used for shafts, studs, bolts, general fabrication
| GRADE | CARBON % | STRENGTH LEVEL | TYPICAL USE |
|---|---|---|---|
| EN 1A | 0.07–0.15 | Low | Free cutting parts |
| SAE 1025 | 0.22–0.28 | Medium | General shafts |
| EN 8 | 0.35–0.45 | Medium-High | Axles, studs |
| EN 9 | 0.50–0.60 | High | Wear parts |
| EN 42 | 0.70–0.85 | Very High | Springs |
| EN 44 | 0.90–1.20 | High Hardness | Blades |
Higher carbon = higher hardness but lower weldability.
2. Case Hardening Steels (Hard Outside, Tough Inside)
Perfect for gears & transmission components
| GRADE | CORE CARBON | KEY ALLOY | BEST FOR |
|---|---|---|---|
| EN 353 | 0.20 max | Cr + Ni | Automotive gears |
| EN 354 | 0.20 max | Higher Ni | Heavy-duty gears |
| EN 355 | 0.20 max | Cr + Ni + Mo | High load shafts |
| 16MnCr5 | 0.14–0.19 | Mn + Cr | Pinions |
| 20MnCr5 | 0.17–0.22 | Mn + Cr | Transmission gears |
| SAE 8620 | 0.18–0.23 | Ni + Cr + Mo | Aircraft parts |
3. Alloy Steels (Strength Added by Cr, Ni, Mo)
Used in high stress components
| GRADE | KNOWN AS | SPECIAL FEATURE |
|---|---|---|
| SAE 4130 | Chromoly | Weldable & strong |
| SAE 4140 | Popular alloy steel | Excellent toughness |
| SAE 4340 / EN 24 | Premium alloy | Aircraft shafts |
| EN 19 | Indian favourite | High tensile strength |
| EN 25 | Nickel rich | Shock resistant |
| EN 30B | High Ni steel | Aerospace |
| SAE 8640 | Mid alloy | Heavy shafts |
4. Spring Steels (Flex Without Breaking)
| GRADE | SILICON % | APPLICATION |
|---|---|---|
| EN 45A | 1.7–2.0 | Leaf springs |
| 60Si7 | 1.5–2.0 | Automotive springs |
| EN 47 | — | Heavy springs |
5. Bearing & Wear Steels
| GRADE | CARBON % | CHROMIUM % | APPLICATION |
|---|---|---|---|
| SAE 52100 | ~1.0 | 1.3–1.6 | Ball bearings |
| EN 31 | ~1.0 | 1.0–1.6 | Rollers, dies |
6. Cold Work Tool Steels
| GRADE | FEATURE |
|---|---|
| D2 | High chromium, wear resistant |
| D3 | Very high carbon |
| M2 | High speed steel |
Hot Work Tool Steels
| GRADE | BEST FOR |
|---|---|
| H11 | Forging dies |
| H13 | Die casting dies |
7. Chrome-Moly (Cr-Mo) Steels
| GRADE | APPLICATION |
|---|---|
| F5 | Boiler tubes |
| F9 | High temperature pipes |
| F11 | Pressure vessels |
| F22 | Refinery piping |
Used in power plants & refineries.
