Product Description
ASTM A498/A498m Seamless Carbon Steel Tubes
1. Standard Specification
ASTM A498/A498M is a standard that focuses on seamless carbon steel tubes used for mechanical and general engineering purposes. The "M" in the standard designation indicates that it is in the metric system. This standard sets requirements for the manufacture, dimensions, mechanical properties, and quality of the seamless carbon steel tubes, ensuring they are suitable for a wide range of applications where reliable mechanical performance is needed.
2. Chemical Composition
The chemical composition of ASTM A498/A498M seamless carbon steel tubes is engineered to offer the right balance of properties. The following table shows the typical chemical composition limits:
|
Element
|
Content (%)
|
|
Carbon (C)
|
0.10 - 0.30
|
|
Manganese (Mn)
|
0.30 - 0.90
|
|
Phosphorus (P)
|
≤ 0.040
|
|
Sulfur (S)
|
≤ 0.040
|
The carbon content in this range provides a good combination of strength and formability. A higher carbon content towards the upper limit can increase the strength and hardness of the steel, while still allowing for reasonable workability during manufacturing processes. Manganese helps in improving the hardenability and strength of the steel. It also acts as a deoxidizer and a desulfurizer, enhancing the overall quality of the steel. The limits on phosphorus and sulfur are set to prevent embrittlement and ensure the steel's toughness and durability. Excessive amounts of these impurities can lead to poor mechanical properties and reduced resistance to cracking.
3. Mechanical Properties
The mechanical properties of ASTM A498/A498M seamless carbon steel tubes are as follows:
|
Property
|
Value
|
|
Tensile Strength (MPa)
|
310 - 550
|
|
Yield Strength (MPa)
|
≥ 170
|
|
Elongation (%)
|
≥ 20
|
|
Hardness (HB)
|
101 - 163
|
The tensile strength range of 310 - 550 MPa indicates the ability of the tubes to withstand stretching forces without breaking. The minimum yield strength of 170 MPa ensures that the tubes can resist permanent deformation under normal operating loads. The elongation of at least 20% shows the ductility of the steel, which is important for manufacturing processes such as bending and flanging. It also allows the tubes to absorb some energy during stress application without fracturing. The hardness range of 101 - 163 HB (Brinell Hardness) is set to ensure that the material has the appropriate resistance to indentation and wear, while still being workable for various mechanical operations.
4. Dimensions
4.1 Outer Diameter
The outer diameter of ASTM A498/A498M seamless carbon steel tubes can vary widely. The standard covers a wide range of sizes, typically from 6.35 mm (0.25 in) to 610 mm (24 in). The following table shows the outer diameter tolerances:
|
Outside Diameter (mm)
|
Tolerance (mm)
|
|
6.35 - 48.26
|
± 0.20
|
|
48.26 - 114.30
|
± 0.38
|
|
114.30 - 219.08
|
± 0.51
|
|
219.08 - 323.85
|
± 0.76
|
|
323.85 - 406.40
|
± 1.02
|
|
406.40 - 610.00
|
± 1.52
|
4.2 Wall Thickness
The wall thickness of the tubes also has specific tolerances. The following table shows the wall thickness tolerances based on the outer diameter:
|
Outside Diameter (mm)
|
Tolerance (%)
|
|
6.35 - 114.30
|
+ 15 / - 12.5
|
|
114.30 - 610.00
|
+ 12.5 / - 10
|
4.3 Length
The tubes are available in standard lengths, which can be either random lengths or cut - to - length. Random lengths typically range from 4 m to 12 m. Cut - to - length tubes can be provided according to customer requirements, with length tolerances as follows:
|
Cut Length (m)
|
Tolerance (mm)
|
|
≤ 6
|
+ 6 / - 0
|
|
6 - 9
|
+ 9 / - 0
|
|
9 - 12
|
+ 12 / - 0
|
5. Manufacturing Process
ASTM A498/A498M seamless carbon steel tubes are manufactured using the seamless process. Initially, a solid billet of carbon steel is heated and pierced to form a hollow shell. This shell is then further processed through hot - rolling or cold - drawing operations to achieve the desired outer diameter and wall thickness. After the forming process, the tubes may undergo heat - treatment such as annealing, normalizing, or quenching and tempering, depending on the final mechanical properties required. Heat - treatment helps to relieve internal stresses, refine the grain structure, and improve the overall mechanical properties of the tubes.
6. Applications
ASTM A498/A498M seamless carbon steel tubes are widely used in various industries due to their mechanical properties and dimensional accuracy:
- Mechanical Engineering: They are used in the construction of machinery parts such as shafts, hydraulic cylinders, and structural components. The high strength and good formability of the tubes make them suitable for machining into complex shapes and for withstanding mechanical stresses.
- Automotive Industry: In automotive manufacturing, these tubes are used in exhaust systems, suspension components, and fuel lines. Their ability to resist corrosion and mechanical wear, along with their dimensional stability, is crucial for automotive applications.
- General Engineering: In applications like conveyor systems, scaffolding, and general - purpose structures, ASTM A498/A498M tubes are preferred for their reliability and cost - effectiveness. They can be easily welded, drilled, and fabricated to meet the specific requirements of different engineering projects.
- Agricultural Equipment: Tubes are used in the construction of agricultural machinery such as tractors, combines, and irrigation systems. Their durability and resistance to environmental factors make them suitable for use in harsh agricultural environments.
7. Testing
To ensure the quality and performance of ASTM A498/A498M seamless carbon steel tubes, several tests are carried out:
- Chemical Analysis: This is done to verify that the chemical composition of the steel meets the specified requirements. Samples are taken from the tubes, and techniques such as spectroscopy are used to determine the exact content of carbon, manganese, phosphorus, sulfur, and other elements.
- Mechanical Tests: Tensile tests are performed to measure the tensile strength, yield strength, and elongation of the tubes. Hardness tests, such as Brinell hardness testing, are carried out to ensure the material has the appropriate hardness. Bend tests and flattening tests are also conducted to assess the formability of the tubes.
- Dimensional Inspection: The outer diameter, wall thickness, and length of the tubes are measured using precision measuring instruments to ensure they are within the specified tolerances. Ultrasonic or radiographic testing may be used to detect internal defects in the tubes.
8. Marking
ASTM A498/A498M tubes are marked in accordance with the standard requirements. The marking typically includes the standard designation (A498/A498M), the manufacturer's name or trademark, the size (outer diameter and wall thickness), and the heat number or lot number. This marking is essential for traceability throughout the supply chain and for quality control purposes.
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