AISI 4320 Round Bar (UNS G43200)
AISI 4320 Round Bar is a nickel–chromium–molybdenum alloy steel primarily designed for carburizing applications. It offers an excellent combination of a tough core with a hard, wear-resistant case after heat treatment. Due to its superior fatigue strength, impact resistance, and deep hardenability, AISI 4320 round bars are widely used in automotive, aerospace, and heavy engineering components.
Key Features
- Ni-Cr-Mo alloy steel for high toughness and strength
- Excellent carburizing characteristics
- High fatigue and impact resistance
- Good hardenability and core strength
- Suitable for quenching, tempering, and case hardening
Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| EN | 20NiCrMo2-2 |
| DIN | 1.6523 |
| JIS | SNCM220 |
| BS | 905M20 |
Sizes
- Diameter: 20 mm to 500 mm
- Length: 3 m, 6 m, or cut-to-length
- Custom sizes available on request
AISI 4320 Chemical Composition
| Element | Percentage (%) |
|---|---|
| Carbon (C) | 0.17 – 0.23 |
| Manganese (Mn) | 0.45 – 0.65 |
| Nickel (Ni) | 1.65 – 2.00 |
| Chromium (Cr) | 0.40 – 0.60 |
| Molybdenum (Mo) | 0.20 – 0.30 |
| Phosphorus (P) | ≤ 0.035 |
| Sulfur (S) | ≤ 0.040 |
| Iron (Fe) | Balance |
4320 Mechanical Properties
| Property | Value |
|---|---|
| Core Tensile Strength | 900 – 1100 MPa |
| Yield Strength | ~650 MPa |
| Elongation | 12 – 16% |
| Case Hardness | 58 – 62 HRC |
| Core Hardness | 30 – 38 HRC |
UNS G43200 Physical Properties
| Property | Value |
|---|---|
| Density | 7.85 g/cm³ |
| Melting Point | ~1425°C |
| Thermal Conductivity | 43.0 W/m·K |
| Modulus of Elasticity | 205 GPa |
Types of AISI 4320 Round Bar
- Hot Rolled Round Bar
- Forged Round Bar
- Peeled Round Bar
- Turned & Polished Round Bar
Applications
- Automotive transmission gears
- Heavy-duty shafts and pinions
- Aerospace landing gear components
- High-stress carburized parts
- Industrial machinery components
- Oil & gas mechanical parts
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