SAE/AISI 4820 Alloy Steel (UNS G48200)
SAE/AISI 4820 is a low-alloy steel containing nickel and molybdenum, offering a combination of good hardenability, toughness, and strength. This versatile material is widely used in components subjected to heavy wear or impact and is available in various forms such as bars, forgings, and plates.
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| Chemical Composition | ||
|---|---|---|
| Element | Min | Max |
| Iron | 94.64% | 95.72% |
| Carbon | 0.18% | 0.23% |
| Manganese | 0.50% | 0.70% |
| Molybdenum | 0.20% | 0.30% |
| Nickel | 3.25% | 3.75% |
| Phosphorous | —— | 0.035% |
| Silicon | 0.15% | 0.30% |
| Sulfur | —— | 0.04% |
The following table provides a list of SAE/AISI 4820 properties in both SI and US customary/Imperial units.
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| Physical Properties | Metric |
|---|---|
| Density | 7850 kg/m3 |
| Mechanical Properties | Metric |
| Tensile Strength (Ultimate) | 685 MPa |
| Tensile Strength (Yield) | 460 MPa |
| Young’s Modulus (E) | 190 - 210 GPa |
| Bulk Modulus (K) | 140 GPa |
| Shear Modulus (G) | 80 GPa |
| Poisson’s Ratio (ν) | 0.27 - 0.30 |
| Brinell Hardness | 197 |
| Thermal Properties | Metric |
| Thermal Conductivity | 44.5 W/m·K |
| Specific Heat Capacity (Cp) | 470 J/kg·K |
| Coefficient of Thermal Expansion (αL) | 1.1×10-5 1/°C |
| Electrical Properties | Metric |
| Electrical Conductivity | 4.41×106 S/m |
| Electrical Resistivity | 2.27×10-7 Ω·m |
The values in this table are approximate and can vary depending on various factors such as the specific manufacturing process and heat treatment applied to the alloy.
Advantages & Disadvantages of 4820 Alloy Steel
| Advantages | Disadvantages |
|---|---|
| High strength | Limited corrosion resistance |
| Good wear resistance | Relatively low hardenability |
| Excellent toughness | Requires proper heat treatment |
| Good machinability | Not suitable for welding |
Applications of 4820 Alloy Steel
Thanks to its blend of strength, toughness, and wear resistance, 4820 alloy steel is commonly used across several engineering and industrial sectors, including:
- Gears and Gear Shafts: Frequently used in the manufacturing of gears, particularly in applications where high strength and wear resistance are essential.
- Axles and Shafts: Employed in the production of axles and shafts, especially in applications involving high stresses due to its excellent toughness and hardenability.
- Forging and Machining Components: Offers good machinability for ease of fabrication and shaping, and is commonly used for forged components like crankshafts, connecting rods, and machinery parts.
- Bearings: Suitable for anti-friction bearings and related components, benefiting from high strength, wear resistance, and hardenability.
- Tooling and Die Manufacturing: Used in tooling and die applications that demand high impact and wear resistance due to its toughness and hardenability.
- Automotive Components: Found in drive shafts, differential gears, and transmission parts, where it withstands heavy loads and harsh operating conditions.