1. Key Properties:
High Strength: SAE 8640 is a low-alloy steel that offers high tensile strength, making it suitable for heavy-duty applications requiring both strength and durability.
Good Toughness: The steel has excellent toughness, ensuring it performs well under shock loading and in dynamic conditions, reducing the likelihood of failure under extreme stresses.
Good Hardening Properties: SAE 8640 responds well to heat treatment processes such as carburizing, quenching, and tempering, which increases surface hardness while maintaining a tough core.
Wear Resistance: After heat treatment, SAE 8640 demonstrates excellent wear resistance, making it ideal for components exposed to friction and high-stress conditions.
Weldability: SAE 8640 has good weldability, though preheating and post-weld heat treatment are recommended for thicker sections to avoid cracking and ensure high-quality joints.
Corrosion Resistance: Offers moderate resistance to corrosion, which can be improved by surface coatings or treatments in harsh environments.
2. Applications/Industries:
Automotive: SAE 8640 is used in the automotive industry for producing high-strength parts such as axles, gears, crankshafts, and transmission components that must withstand high stress and wear.
Heavy Machinery: It is widely used in the manufacturing of components for heavy machinery, including shafts, gears, and pressure vessels, where high toughness and strength are essential for operation in demanding environments.
Oil & Gas: SAE 8640 is commonly used in the oil and gas industry for critical components like pump shafts, valves, and wellhead equipment, which must endure high pressures and harsh conditions.
Military: Used in the defense industry for manufacturing armored vehicle components, weapon systems, and high-strength tools that are subjected to high impact and wear.
Aerospace: SAE 8640 is used in aerospace applications such as structural components, landing gears, and turbine engine parts, where high strength, toughness, and fatigue resistance are crucial.
3. Certifications/Standards:
SAE J403: SAE 8640 conforms to the SAE J403 standard for alloy steels, ensuring it meets the required chemical composition and mechanical properties.
ASTM A519: This standard applies to seamless carbon and alloy steel mechanical tubing, which is relevant for SAE 8640 seamless pipes.
ISO 9001: Quality management system certification.
4. Chemical Composition:
Carbon (C): 0.36% – 0.44%
Manganese (Mn): 0.70% – 1.00%
Chromium (Cr): 0.70% – 1.00%
Nickel (Ni): 1.50% – 2.00%
Molybdenum (Mo): 0.15% – 0.25%
Silicon (Si): 0.20% – 0.35%
Phosphorus (P): 0.035% max
Sulfur (S): 0.035% max
Iron (Fe): Balance
5. Technical Specifications:
Yield Strength:
SAE 8640: 450 MPa (minimum)
Tensile Strength:
SAE 8640: 655–850 MPa
Hardness:
SAE 8640: Approximately 200–250 HB (Brinell hardness) in the as-rolled condition. After heat treatment (carburizing or quenching), surface hardness can reach up to 58–60 HRC.