Product Description
ASTM A498/A498M Welded Carbon Steel Tubes
1. Standard Specification
ASTM A498/A498M is a standard that pertains to welded carbon steel tubes, with the "M" indicating metric units. This standard outlines requirements for the manufacturing process, dimensions, mechanical properties, and quality of the tubes. It ensures that the welded carbon steel tubes are suitable for mechanical and general engineering applications where reliable performance is crucial. The standard also specifies procedures for testing and inspection to guarantee compliance with the set criteria.
2. Chemical Composition
The chemical composition of ASTM A498/A498M welded carbon steel tubes is designed to provide the necessary 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
|
Carbon within this range balances strength and formability. Higher carbon content towards the upper limit can enhance strength and hardness, while still allowing for workability during manufacturing, especially important for the welding process. Manganese improves hardenability and strength, and also acts as a deoxidizer and desulfurizer, contributing to the overall quality of the steel. The restricted levels of phosphorus and sulfur prevent embrittlement, ensuring the steel's toughness and durability. Excessive amounts of these impurities can lead to poor mechanical properties and reduced resistance to cracking, particularly at the weld joints.
3. Mechanical Properties
The mechanical properties of ASTM A498/A498M welded 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 tubes' ability to withstand stretching forces without failure. The minimum yield strength of 170 MPa ensures they can resist permanent deformation under normal operating loads. An elongation of at least 20% shows the steel's ductility, which is beneficial for both the manufacturing process, including bending and flanging operations, and for the tubes' ability to absorb energy during stress application without fracturing. The hardness range of 101 - 163 HB (Brinell Hardness) ensures the material has appropriate resistance to indentation and wear, while still being workable for various mechanical operations. However, it should be noted that the weld region may have slightly different mechanical properties compared to the base metal, and proper welding procedures are crucial to maintain overall performance.
4. Dimensions
4.1 Outer Diameter
The outer diameter of ASTM A498/A498M welded carbon steel tubes can vary widely. The standard typically covers sizes 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 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 usually 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 welded carbon steel tubes are produced through a welding process. First, a flat strip of carbon steel is formed into a tubular shape, and then the edges are welded together. The welding methods can include electric resistance welding (ERW), submerged arc welding (SAW), or other suitable welding techniques. After welding, the tubes may undergo additional processing such as straightening, sizing, and heat - treatment. Heat - treatment, which can be annealing, normalizing, or stress - relieving, helps to relieve internal stresses generated during the welding process, improve the mechanical properties of the weld and the base metal, and enhance the overall quality of the tubes.
6. Applications
ASTM A498/A498M welded carbon steel tubes find wide applications in various industries due to their mechanical properties and dimensional accuracy:
- Mechanical Engineering: They are used in the construction of machinery parts such as frames, brackets, and some non - critical shafts. The tubes' strength and formability make them suitable for machining and fabricating into different shapes to meet the requirements of mechanical systems.
- Automotive Industry: In automotive manufacturing, these tubes are used in some structural components, such as parts of the vehicle frame and some non - pressure - bearing exhaust system components. Their cost - effectiveness, along with adequate mechanical properties, makes them a viable choice for such applications.
- General Engineering: In applications like conveyor systems, handrails, and some light - duty structural frameworks, ASTM A498/A498M welded tubes are preferred for their reliability and relatively lower cost compared to some other materials. They can be easily welded, drilled, and fabricated to fit the specific needs of different engineering projects.
- Agricultural Equipment: Tubes are used in the construction of agricultural machinery like fencing, some parts of tractors, and simple irrigation piping systems. Their durability and resistance to the agricultural environment, along with cost - efficiency, make them suitable for these applications.
7. Testing
To ensure the quality and performance of ASTM A498/A498M welded 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, including the base metal and the weld area, and techniques such as spectroscopy are used to determine the exact content of carbon, manganese, phosphorus, sulfur, and other elements. This is important to ensure the quality of the raw material and the compatibility of the weld filler material if used.
- Mechanical Tests: Tensile tests are performed to measure the tensile strength, yield strength, and elongation of the tubes. Special attention is paid to the weld region to ensure it meets the required mechanical properties. Hardness tests, such as Brinell hardness testing, are carried out on both the base metal and the weld to check for any significant differences. Bend tests and flattening tests are also conducted to assess the formability of the tubes, especially in the area around the weld.
- 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. In addition, the weld quality is inspected for proper penetration, bead shape, and absence of defects such as porosity, cracks, and incomplete fusion. Non - destructive testing methods like ultrasonic testing or radiographic testing may be used to detect internal defects in the weld and the tube body.
8. Marking
ASTM A498/A498M welded carbon steel 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), the type of welding process used (e.g., ERW, SAW), and the heat number or lot number. This marking is essential for traceability throughout the supply chain and for quality control purposes, allowing for easy identification and tracking of the tubes from production to end - use.
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