1. Key Properties:
High Strength: SAE 4120 is an alloy steel with strong tensile and yield strength, ideal for high-stress and high-pressure applications.
Good Toughness: Offers excellent toughness, making it highly resistant to impact and shock loads.
Weldability: It has good weldability, allowing it to be easily joined and fabricated for various structural and mechanical applications.
Corrosion Resistance: Provides moderate resistance to corrosion in typical industrial environments.
Heat Treatable: SAE 4120 can be heat-treated to enhance its mechanical properties, improving hardness and strength for specific uses.
2. Applications/Industries:
Automotive: Commonly used in manufacturing high-strength parts like gears, axles, and shafts that must withstand heavy loads.
Heavy Machinery: Suitable for components like crankshafts, connecting rods, and other parts subject to high stress and wear.
Oil & Gas: Frequently used for drilling equipment, pipelines, and other components in the oil and gas industry where strength and durability are essential.
Aerospace: Employed for aerospace components that require both strength and toughness, including engine parts and structural elements.
Hydraulic Systems: Used in hydraulic cylinders, pistons, and rods where high strength and good machinability are required.
3. Certifications/Standards:
SAE J403: SAE 4120 conforms to the SAE J403 standard for alloy steels, specifying chemical composition and mechanical properties.
ASTM A519: This specification applies to seamless carbon and alloy steel mechanical tubing, which is relevant for SAE 4120 pipes.
ISO 9001: Quality management system certification.
4. Chemical Composition:
Carbon (C): 0.18% – 0.23%
Manganese (Mn): 0.60% – 0.90%
Chromium (Cr): 0.90% – 1.20%
Molybdenum (Mo): 0.15% – 0.25%
Silicon (Si): 0.20% max
Phosphorus (P): 0.035% max
Sulfur (S): 0.035% max
Iron (Fe): Balance
5. Technical Specifications:
Yield Strength:
SAE 4120: 415 MPa (minimum)
Tensile Strength:
SAE 4120: 585–735 MPa
Hardness:
SAE 4120: Approximately 197–255 HB (Brinell hardness)