Products Description
Product Specifications
| Standards |
ASTM A519 / ASME SA519 |
| Steel Grades | E3310,4012,4023,4024,4027,4028,4037,4042 4047,4063,4118,4130,4135,4137,4140,4142,etc. |
| Equivalent Standards | EN 10297-1 / JIS G3441/ GB/T 8162 |
| Outer Diameter (OD) | 5mm-630mm |
| Wall Thickness (WT) | 1.5mm-50mm |
| Length | 6/12 m |
| Surface Treatment | Black, oiled, pickled, or bright finish |
| Production Process | cold drawing over mandrel |
| Condition | +SR / +N / Q&T (customer specified) |
Following stress-relieving or quench-and-temper treatment, 4140 DOM tubing offers a minimum yield strength of 690 MPa (100 ksi) and an exceptional high-pressure load-bearing capacity; compared to 1026 DOM tubing, it allows for a reduction in cylinder wall thickness of over 25% when manufacturing hydraulic cylinders designed for the same operating pressure.
The DOM process achieves an internal surface roughness of Ra ≤ 1.6 μm and maintains strict control over inner diameter tolerances (H8–H9 grades). Thanks to this precise dimensional accuracy, the tubing integrates seamlessly with piston seals, significantly reducing hydraulic fluid leakage and frictional losses.
Unlike traditional hard-chrome-plated piston rods (such as Ck45/1045 steel) that require extensive boring, 4140 DOM precision steel tubing reduces machining allowances by 30%.
Customized Services
- TORICH offers deep-hole honing services, achieving inner diameter tolerances of H7 and bore surface roughness of Ra 0.4–0.8 μm (mirror-like finish).
- We provide wear-resistant and anti-corrosion surface plating, including hard chrome plating for the bore (with a coating thickness of 0.03–0.15 mm per side and hardness of HV 800–1000 / HRC 60+) and hard chrome plating for the outer diameter.
- Services also include internal and external threading (UNF, metric M-threads, and trapezoidal/buttress threads), sealing groove boring, and the machining of J-type, V-type, or U-type weld bevels.
Chemical Composition
| Element | C | Mn | Si | Cr | Mo | P (max) | S (max) |
| 4140 | 0.38–0.43 | 0.75–1.00 | 0.15–0.35 | 0.80–1.10 | 0.15–0.25 | 0.035 | 0.040 |
Mechanical Properties
| Property | Tensile Strength (MPa) | Yield Strength (MPa) | Elongation (%) | Hardness (HB) |
| 4140 Q&T | 850–1000 | 655–850 | 15–25 | 197–235 |
Possible Alternative Grades
- 4130 is a lower-carbon version of 4140; it offers superior weldability, is easier to heat-treat, and is more cost-effective, making it suitable for light-to-medium-duty pneumatic and low-pressure hydraulic cylinders operating at pressures of 25 MPa or less.
- 4340 incorporates nickel into the chromium-molybdenum alloy base, resulting in overall mechanical properties that are 15% superior to those of 4140; it is suitable for applications in aerospace, defense, and large-scale mining machinery.
- EN 10297-1 42CrMo4 and JIS G3441 SCM440 are equivalent standards to 4140, with chemical compositions that correspond almost exactly to those of 4140.
application areas
ASTM A519 4140 DOM tube is widely used in the manufacture and assembly of various high-performance hydraulic and pneumatic cylinders across these sectors:
- Construction Machinery: Boom and bucket cylinders for excavators, loaders, and bulldozers
- Mining and Tunneling Equipment: Hydraulic support legs, jacks, and propulsion cylinders for tunnel boring machines (TBMs)
- Industrial Equipment: Mold-clamping and ejection cylinders for injection molding machines, die-casting machines, and presses
- Heavy-Duty Vehicles: Dump truck hoist cylinders; crane outrigger and telescopic boom cylinders
- Energy and Marine: Offshore platform leveling systems; gate operating cylinders for hydroelectric power stations
- Pneumatic Systems: High-pressure breathing air cylinders; high-pressure air compressor cylinders
Products Show
Testing Equipment
Factory Equipment
Pickling equipment
Products Package
FAQ
Q: What is the delivery hardness of 4140 DOM tube, and is it suitable for further processing?
A: It is supplied in a stress-relieved annealed condition, with hardness typically controlled between HRC 22 and 32. This range ensures good wear resistance while fully accommodating subsequent milling, drilling, and tapping operations.
Q: What are the differences between ASTM A519 4140 DOM tubing and 4140 Quenched and Tempered (QT) bar stock?
A: DOM tubing is used in the cold-drawn state, offering high base strength and good toughness. In contrast, 4140 QT bar stock requires rough machining followed by heat treatment, involving a longer production process. DOM tubing is more cost-effective and better suited for direct use as cylinder barrels.
Q: Can you supply honed tubing with an H7 internal diameter tolerance?
A: Certainly. While DOM tubing typically comes with an H8 tolerance, if your sealing requirements are extremely stringent, we can perform additional deep-hole honing to achieve H7 tolerance, as well as superior roundness and straightness.
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