AISI 4140 Round Bar (UNS G41400)
AISI 4140 Round Bar is a chromium-molybdenum alloy steel known for its high strength, toughness, and excellent fatigue resistance. With higher carbon content than 4130, this grade offers superior hardenability and wear resistance, making it one of the most widely used alloy steels for heavy-duty mechanical and structural applications. AISI 4140 round bars perform exceptionally well in quenched & tempered condition.
Key Features
- Chromium-molybdenum alloy steel with high strength
- Excellent hardenability and wear resistance
- Very good toughness and impact strength
- Good machinability in annealed or Q&T condition
- Suitable for induction and flame hardening
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| EN | 42CrMo4 |
| DIN | 1.7225 |
| JIS | SCM440 |
| BS | 708M40 |
AISI 4130 Round Bar Sizes
- Diameter: 6 mm to 600 mm
- Length: 3 m, 6 m, or cut-to-length
- Custom sizes available on request
AISI 4140 Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.38 – 0.43 |
| Manganese (Mn) | 0.75 – 1.00 |
| Chromium (Cr) | 0.80 – 1.10 |
| Molybdenum (Mo) | 0.15 – 0.25 |
| Silicon (Si) | 0.15 – 0.35 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.040 |
| Iron (Fe) | Balance |
4140 Mechanical Properties
| Property | Value |
|---|---|
| Tensile Strength | 850 – 1000 MPa |
| Yield Strength | 650 – 850 MPa |
| Elongation | 12 – 18% |
| Hardness | 28 – 32 HRC |
UNS G41400 Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | ~1430°C |
| Thermal Conductivity | 42.6 W/m·K |
| Modulus of Elasticity | 205 GPa |
Types of AISI 4130 Round Bar
- Hot Rolled Round Bar
- Cold Drawn Round Bar
- Bright Round Bar
- Turned & Polished Round Bar
- Quenched & Tempered (Q&T) AISI 4130 Round Bar
Applications
- Heavy-duty shafts and axles
- Gears, pinions, and crankshafts
- Oil & gas drilling tools and components
- Automotive and aerospace parts
- Tooling, dies, and machine components
- Structural parts requiring high fatigue strength
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