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AISI 8740 Alloy Steel | UNS G87400 Steel Bar
- John
When selecting the ideal material for high-stress applications, AISI 8740 steel is a top contender. This alloy steel is specifically engineered to withstand the toughest conditions.
So, what makes AISI 8740 so reliable? In this article, we will examine the properties and products of AISI 8740 steel.
SteelPro Group, with its commitment to high-quality materials and expert support, is here to ensure you get the best AISI 8740 steel for your specific needs.
What Is 8740 Steel?
AISI 8740 steel is a high-strength, low-alloy steel. The combination of Cr and Ni improves its corrosion resistance, while Mo enhances its performance at high temperatures. This steel resists wear, fatigue, and impact. It is commonly used in critical applications such as gears, shafts, and fasteners. Its machinability allows it to be shaped into precise, complex components.
8740 Steel Chemical Composition
| Elements | Content(wt%) |
| Carbon (C) | 0.38~0.43 |
| Silicon (Si) | 0.15~0.35 |
| Manganese (Mn) | 0.75~1.00 |
| Phosphorus (P) | ≤0.035 |
| Sulfur (S) | ≤0.04 |
| Chromium (Cr) | 0.4~0.6 |
| Nickel (Ni) | 0.4~0.7 |
| Molybdenum (Mo) | 0.2~0.3 |
8740 Steel Mechanical Properties
| Property | Metric Value | Imperial Value |
| Hardness, Brinell | 269 HB | 269 HB |
| Hardness, Knoop | 294 HK | 294 HK |
| Hardness, Rockwell B | 99 HRB | 99 HRB |
| Hardness, Rockwell C | 27 HRC | 27 HRC |
| Hardness, Vickers | 284 HV | 287 HV |
| Tensile Strength, Ultimate | 938 MPa | 136,000 psi |
| Tensile Strength, Yield | 620 MPa | 89,900 psi |
| Elongation at Break | 0.16 | 0.16 |
| Modulus of Elasticity | 205 GPa | 29,700 ksi |
| Bulk Modulus | 160 GPa | 23,200 ksi |
| Poisson’s Ratio | 0.29 | 0.29 |
| Machinability | 0.65 | 0.65 |
| Shear Modulus | 80.0 GPa | 11,600 ksi |
| Izod Impact | 18.0 J | 13.3 ft-lb |
8740 Steel Physical Properties
| Property | Metric Value | Imperial Value |
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Melting Point | 1425-1510°C | 2597-2750°F |
| Thermal Conductivity | 40 W/m·K | 23.2 BTU·ft/hr·°F/in |
| Specific Heat Capacity | 0.475 J/g·°C | 0.114 BTU/lb·°F |
| Thermal Conductivity | 46.6 W/m·K | 323 BTU·in/hr·ft²·°F |
8740 Steel Applications
- Gears
- Shafts
- Fasteners
- Crankshafts
- Axles
- Roller Bearings
We collaborate with leading manufacturers to supply high-quality AISI 8740 steel for aerospace, automotive, and industrial applications. Our materials meet rigorous industry standards for performance and durability.
8740 Steel Product Forms and Size
Selecting the right steel for your project is crucial, and 8740 steel offers a range of product forms and sizes to suit your needs. SteelPro Group also offers tailored sizing solutions, guaranteeing that you receive the precise measurements needed for your project.
Round Bars
- Diameter: 6.35 mm ~ 254 mm (0.25 in ~ 10 in)
Square Bars
- Size: 6.35 mm ~ 152 mm (0.25 in ~ 6 in)
Flat Bars
- Width: 12.7 mm ~ 305 mm (0.5 in ~ 12 in)
- Thickness: 6.35 mm ~ 50.8 mm (0.25 in ~ 2 in)
Plates
- Thickness: 6.35 mm ~ 101.6 mm (0.25 in ~ 4 in)
- Width: 305 mm ~ 3048 mm (12 in ~ 120 in)
- Length: 3048 mm ~ 12192 mm (120 in ~ 480 in)
AISI 8740 Steel Specifications
| Category | Specifications |
| AMS | AMS 6322, AMS 6322F, AMS 6323, AMS 6323D, AMS 6325, AMS 6325D, AMS 6327D, AMS 6358, AMS 6358B, AMS 6327, AMS 7496 |
| ASTM | ASTM A322, ASTM A331, ASTM A505, ASTM A519, ASTM A29, ASTM A752, ASTM A320 (L7C, L73) |
| SAE | SAE J770, SAE J412, SAE J1397, SAE J404 |
AISI 8740 Steel Key Characteristic
Advantages
- Superior Strength and Durability: AISI 8740 provides outstanding robustness and resilience for demanding applications.
- Wear and Fatigue Resistance: It is highly durable and maintains its strength under continuous pressure and repetitive use.
- Corrosion Resistance: Chromium and nickel improve its ability to resist corrosion.
- Good Machinability: AISI 8740 can be machined with the right tools.
Disadvantages
- Welding Issues: Welding demands proper preheating and post-weld heat treatment to prevent fractures and ensure the weld’s integrity.
- Cost: The alloying elements make it more expensive than simpler steel.
- Brittleness with Incorrect Heat Treatment: Improper heat treatment can cause brittleness.
- Limited High-Temperature Use: It may not perform well in extremely high-temperature environments without additional treatments.
Partner with SteelPro Group for Top-Quality 8740 Steel
SteelPro Group is proud to offer the highest quality AISI 8740, meeting rigorous industry standards. We also provide other materials like hot rolled 4140 plate. Our experienced team is prepared to provide tailored solutions and support for all your steel needs. We provide:
- Custom Cutting: Tailored to your specifications for precise sizes and shapes.
- Surface Treatment: Including carburizing, nitriding, and protective coating.
- Heat Treatment: Quenching, tempering, and stress-relieving to achieve the desired mechanical properties.
- Machining: Precision machining for complex components, including turning, milling, and grinding for parts like shafts, gears, and axles.
Contact us today to discuss how AISI 8740 can power your next project with strength and durability.
