SAE/AISI 4118 Alloy Steel (UNS G41180)
SAE/AISI 4118 steel is commonly used in applications that require a combination of strength and toughness, such as gears, shafts, bolts, and other mechanical components.
| Chemical Composition | ||
|---|---|---|
| Element | Min | Max |
| Iron | 97.70% | 98.49% |
| Carbon | 0.18% | 0.23% |
| Chromium | 0.40% | 0.60% |
| Manganese | 0.70% | 0.90% |
| Molybdenum | 0.08% | 0.15% |
| Phosphorous | 0.035% | |
| Silicon | 0.15% | 0.35% |
| Sulfur | 0.04% | |
The following table provides a list of SAE/AISI 4118 properties in both SI and US customary/Imperial units.
Click on the icon to switch between Metric and Imperial units.
| Physical Properties | Metric |
|---|---|
| Density | 7850 kg/m3 |
| Mechanical Properties | Metric |
| Tensile Strength (Ultimate) | 517 MPa |
| Tensile Strength (Yield) | 365 MPa |
| Young’s Modulus (E) | 190 - 210 GPa |
| Bulk Modulus (K) | 140 GPa |
| Shear Modulus (G) | 80 GPa |
| Elongation at Break | 33% |
| Reduction of Area | 64% |
| Poisson’s Ratio (ν) | 0.27 - 0.30 |
| Brinell Hardness | 137 |
| Thermal Properties | Metric |
| Thermal Conductivity | 44.5 W/m·K |
| Specific Heat Capacity (Cp) | 470 J/kg·K |
| Coefficient of Thermal Expansion (αL) | 1.3×10-5 1/°C |
| Electrical Properties | Metric |
| Electrical Conductivity | 4.18×106 S/m |
| Electrical Resistivity | 2.4×10-7 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 4118 Alloy Steel
| Advantages | Disadvantages |
|---|---|
| High strength and toughness | Moderate corrosion resistance |
| Good hardenability and wear resistance | Lower machinability compared to some steels |
| Can be heat treated for desired properties | Limited weldability |
| Cost-effective compared to some specialty steels | Susceptible to surface cracking during heat treatment |
Applications of 4118 Alloy Steel
AISI 4118 steel is commonly used in various applications that require a combination of strength, toughness, and wear resistance. Some of the typical applications of AISI 4118 steel include:
- Gears and Gear Shafts: AISI 4118 steel is often utilized in the manufacturing of gears and gear shafts due to its high strength, good hardenability, and wear resistance.
- Bolts and Fasteners: The high strength and toughness of AISI 4118 steel make it suitable for use in bolts, studs, and other fasteners.
- Mechanical Components: AISI 4118 steel finds application in various mechanical components such as shafts, axles, crankshafts, and connecting rods.
- Automotive Parts: Due to its excellent mechanical properties, AISI 4118 steel is used in the automotive industry for manufacturing parts like crankshafts, transmission components, and steering system parts.
- Machine Tools and Equipment: AISI 4118 steel is employed in the production of machine tool components, such as spindles, gears, and shafts.
- Construction and Mining Equipment: In industries such as construction and mining, AISI 4118 steel is utilized for manufacturing various equipment components like pins, bushings, and wear-resistant parts.
- Agricultural Machinery: AISI 4118 steel is employed in the manufacturing of agricultural machinery components like axles, pins, and shafts.