Drawn Over Mandrel Tubing ERW Welded Alloy Steel Tube For Mechanical Equipment
Drawn Over Mandrel Tubing ERW Welded Alloy Steel Tube For Mechanical Equipment
Drawn‑Over‑Mandrel (DOM) ERW welded alloy steel tube is produced by cold‑drawing electric‑resistance‑welded (ERW) tube through a mandrel to achieve precise dimensions, smooth inner surfaces, and enhanced mechanical properties. It combines the cost‑efficiency of ERW fabrication with mechanical performance approaching that of seamless tubing. Typical outside diameters range from 12 mm to 114 mm, wall thicknesses from 1.5 mm to 6 mm, and lengths up to 12 m, with tolerances meeting or exceeding ASTM A519 DOM requirements. Its high yield strength, tight dimensional tolerances, and excellent surface finish make it ideal for precision mechanical components.
Material Description
Drawn‑Over‑Mandrel tubing begins as ERW strip steel that is longitudinally welded, then cold‑drawn through a mandrel. The cold‑drawing process refines the microstructure, eliminates weld‑zone discontinuities, and imparts higher strength and better circularity than as‑welded ERW. The base alloy is controlled‑chemistry carbon–molybdenum steel, offering a balanced combination of strength, toughness, and machinability.
Specifications
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Outside Diameter (OD): 12 mm – 216 mm
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Wall Thickness: 1 mm – 80 mm
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Length: Up to 12 m (custom lengths available)
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Tolerances (OD/Wall): ± 0.05 mm / ± 0.10 mm (in accordance with ASTM A519 DOM)
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Surface Finish: Inner Ra ≤ 0.8 µm; outer black‑drawn or optional polishing
Chemical Composition
| Grade | C (%) | Mn (%) | Si (%) | Cr (%) | Mo (%) | Ni (%) | P (max) (%) | S (max) (%) |
|---|---|---|---|---|---|---|---|---|
| AISI 1026 | 0.22–0.28 | 0.60–0.90 | 0.15–0.35 | – | – | – | ≤ 0.040 | ≤ 0.050 |
| AISI 4130 | 0.280–0.330 | 0.40–0.60 | 0.15–0.30 | 0.80–1.10 | 0.15–0.25 | – | 0.035 | 0.040 |
| AISI 4140 | 0.380–0.430 | 0.75–1.00 | 0.15–0.30 | 0.80–1.10 | 0.15–0.25 | – | 0.035 | 0.040 |
| AISI 4340 | 0.370–0.430 | 0.600–0.800 | 0.150–0.300 | 0.700–0.900 | 0.200–0.300 | 1.65–2.00 | ≤ 0.035 | ≤ 0.040 |
| AISI 8620 | 0.18–0.23 | 0.70–0.90 | – | – | – | – | – | – |
Mechanical Properties
| Grade | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) |
|---|---|---|---|
| AISI 1026 | 490 | 415 | 15 |
| AISI 4130 | 560 | 460 | 21.5 |
| AISI 4140 | 655 | 415 | 25.7 |
| AISI 4340 | 930–1080 | 830–980 | ≥ 12 |
| AISI 8620 | ~540 | ~385 | ~20 |
Key Features
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High Precision: Tight dimensional tolerances and excellent roundness.
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Enhanced Strength: Cold‐drawing yields yield strengths up to ~980 MPa for high‐alloy grades.
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Smooth Internal Surface: Ideal for hydraulic cylinder liners and bearing applications.
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Good Machinability: Especially in annealed condition for ease of fabrication.
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Uniform Properties: Controlled weld‐zone microstructure for consistent performance.
Standards Conformance
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ASTM A519/A519M: Standard specification for ERW mechanical tubing – DOM condition.
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EN 10305-1/2: Cold‐drawn welded precision steel tubes – non‐alloy and alloy steel.
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GOST 8732-78: Seamless precision steel tubes – cold‐finished.
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JIS G3445: Carbon steel tubes for mechanical structuring – cold‐drawn.
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GB 3639: Cold‐drawn carbon steel precision seamless tubes.
Application Areas
General Fields:
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Hydraulics & Pneumatics: Cylinder rods, liners, pistons.
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Automotive: Steering components, suspension links, transmission shafts.
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Industrial Machinery: Gear shafts, pins, rollers.
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Aerospace & Defense: Landing‐gear actuators, control linkages.
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Construction Equipment: Hydraulic booms, jack legs.
Specific Uses Within Each Field:
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Hydraulic Cylinders: DOM tube liners for smooth sealing and minimal wear.
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Steering Systems: Tie rods and drag links requiring high fatigue strength.
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Gear Assemblies: Precision bore tubes for pinion and roller shafts.
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Landing‐Gear Actuators: Tubes with fatigue‐resistant microstructure.
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Crane Booms & Jacking Systems: High-strength tubes resisting bending and torsion.
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