SAE 4340 40CrNiMoA Alloy Steel Pipe

Product Introduction

SAE 4340 (also known as 40CrNiMoA in China) is a high-strength, low-alloy steel known for its toughness, strength, and resistance to impact and fatigue. It is commonly used in critical engineering applications where these properties are essential. Seamless steel pipes made from SAE 4340 are favored in industries such as aerospace, automotive, and heavy machinery.

Characteristics of SAE 4340 Alloy Pipe

High Strength: Offers exceptional tensile and yield strength.
Excellent Toughness: Maintains toughness and ductility, even under extreme conditions.
Fatigue Resistance: Superior resistance to fatigue, making it ideal for cyclic loading applications.
Good Hardness: Can achieve high hardness levels through heat treatment.
Impact Resistance: Excellent impact resistance, suitable for high-stress environments.

SAE 4340 Alloy Pipe Material

SAE 4340 contains several alloying elements that contribute to its high performance:

Nickel (Ni): Enhances toughness and impact resistance.
Chromium (Cr): Improves hardness and wear resistance.
Molybdenum (Mo): Increases hardenability and strength.
Carbon (C): Contributes to the overall strength and hardness.

Application of SAE 4340 Alloy Pipe

Aerospace: Used in landing gear, shafts, and other structural components.
Automotive: Ideal for crankshafts, gears, and axles.
Oil and Gas: Suitable for high-pressure drill pipes and tubing.
Heavy Machinery: Applied in the construction of heavy-duty equipment and machinery parts.
Military: Utilized in the manufacture of high-strength weapon components.

Process Flow of SAE 4340 Alloy Pipe

Raw Material Selection: High-quality alloy steel is selected for processing.
Hot Rolling/Cold Drawing: Pipes are formed through hot rolling or cold drawing processes to achieve the desired dimensions.
Heat Treatment: Includes normalizing, quenching, and tempering to obtain the required mechanical properties.
Inspection: Conduct rigorous tests such as ultrasonic testing, hydrostatic testing, and dimensional inspections.
Finishing: Surface treatment and final quality checks ensure compliance with standards.

Chemical Compositions (%)

Element	Composition (%)
C	0.38 – 0.43
Si	0.15 – 0.35
Mn	0.60 – 0.80
Cr	0.70 – 0.90
Ni	1.65 – 2.00
Mo	0.20 – 0.30
P	≤ 0.035
S	≤ 0.040

Mechanical Properties

Property	Value
Tensile Strength	930 – 1080 MPa
Yield Strength	745 MPa
Elongation	12%
Reduction of Area	45%
Impact Toughness	≥ 47 J
Hardness	248 – 302 HB

Wall Thickness (W.T.) Tolerance

Seamless Pipes: ±12.5% of the nominal wall thickness.

Inspection and Testing

To ensure the high quality and performance of SAE 4340 alloy pipes, a series of rigorous inspection and testing procedures are implemented:

Visual Inspection: Preliminary examination for surface defects and overall appearance.
Dimensional Inspection: Verification of pipe dimensions, including outer diameter, wall thickness, and length, to ensure compliance with specified tolerances.
Non-Destructive Testing (NDT):
- Ultrasonic Testing (UT): Detects internal defects such as cracks and inclusions.
- Magnetic Particle Testing (MT): Identifies surface and near-surface discontinuities.
- Radiographic Testing (RT): Examines the internal structure for any anomalies.
Hydrostatic Testing: Ensures the pipe can withstand specified pressure without leaking.
Mechanical Testing:
- Tensile Test: Measures tensile strength, yield strength, and elongation.
- Hardness Test: Determines the hardness value to ensure the material meets specified requirements.
- Impact Test: Assesses toughness, particularly at low temperatures.
Chemical Analysis: Confirms the chemical composition of the alloy to ensure it meets the required specifications.

Packaging and Delivery

Proper packaging and handling of SAE 4340 seamless steel pipes are crucial to prevent damage during transportation and storage:

Packaging:
- Pipes are typically bundled and secured with steel strips.
- Ends are capped to prevent contamination.
- Protective coatings may be applied to prevent rust and corrosion.
Marking:
- Each pipe is marked with relevant details such as grade, size, heat number, and manufacturer’s name.
Documentation:
- Comprehensive documentation accompanies the shipment, including inspection and testing certificates, material test reports (MTR), and compliance certificates.

Advantages of SAE 4340 Seamless Steel Pipe

Exceptional Strength and Toughness: Suitable for high-stress and high-impact applications.
Good Machinability: Can be easily machined and fabricated into complex shapes.
Heat Treatable: Excellent response to heat treatment, allowing for a wide range of mechanical properties.
Versatility: Used across various industries, including aerospace, automotive, oil and gas, and heavy machinery.
Fatigue and Wear Resistance: Ideal for components subjected to repetitive stress and harsh conditions.

Summary

SAE 4340 (40CrNiMoA) seamless steel pipes are essential components in many high-stress and high-impact applications. Their exceptional mechanical properties, toughness, and resistance to fatigue and wear make them suitable for demanding environments. Through stringent manufacturing, inspection, and testing processes, these pipes ensure reliability and longevity in service.

For more detailed specifications, technical support, or to place an order, please contact the manufacturer or refer to the relevant industry standards.