4140 Honed Tube

What is a 4140 Honed Tube?

A 4140 Honed Tube is a precision-machined steel tube made from chromium-molybdenum alloy steel (SAE 4140). It is honed internally to achieve a smooth bore with tight dimensional tolerance, usually H8, and surface roughness of Ra ≤ 0.2 μm. These properties make it ideal for use as a hydraulic cylinder barrel, where both strength and precision are critical.

Unlike ordinary cold drawn or seamless tubes, 4140 honing pipe is manufactured specifically for fluid power systems. It can withstand high operating pressure, repeated shock loads, and dynamic movement while maintaining dimensional integrity and sealing performance.

Why Choose 4140 Honed Tube?

The choice of 4140 honed pipe is all about performance. Hydraulic cylinders used in heavy-duty equipment need cylinder tubes that can handle intense working conditions. Here’s what makes 4140 an ideal material:

• High Tensile Strength: Minimum yield strength of around 655 MPa (95,000 psi), suitable for heavy machinery.

• Superior Fatigue Resistance: Withstands cyclic loading in hydraulic systems.

• Enhanced Hardness: After heat treatment (Q&T), it achieves a hardness of 28–32 HRC.

• Good Machinability: Despite its strength, it can be machined, honed, and welded effectively.

• Corrosion Resistance (when treated): Can be paired with internal chrome plating or external coatings.

Technical Specifications

Applications of 4140 Honed Tube

The 4140 honed tube is widely used in industries where high-performance hydraulic systems are essential. Applications include:

• Hydraulic Cylinders:
  Main use in construction equipment, agricultural machinery, and mining systems.

• Telescopic Cylinders:
  Multiple-stage cylinders for dump trucks or lifting arms.

• Press Machines & Industrial Tools:
  Machines requiring high-pressure fluid systems.

• Heavy Equipment Manufacturing:
  Including cranes, loaders, and material handling machines.

• Marine & Offshore Equipment:
  Where corrosion resistance and strength are both essential.

Manufacturing Process

1. Raw Material Preparation:
   Selected from high-quality seamless 4140 alloy steel tubes.

2. Heat Treatment:
   Quenching and tempering (Q&T) to improve mechanical properties.

3. Skiving:
   Internal surface is machined to remove imperfections and ensure roundness.

4. Honing:
   Precision honing achieves mirror-like smoothness and tight tolerances.

5. Final Inspection:
   Dimensional, surface, and hardness checks are carried out on each tube.

6. Surface Treatment & Packaging:
   Tubes are coated with anti-corrosion oil or film and packed for shipment.

Product Advantages

• High Pressure Resistance – Suitable for working pressures up to 350 bar and above

• Ready to Assemble – No additional machining required

• Long Service Life – Reduced seal wear thanks to smooth bore

• High Precision Fit – ID tolerance H8, ideal for piston-to-barrel fit

• Versatile – Suitable for welding, machining, and chrome plating if needed

Quality Assurance & Testing

Each 4140 honed pipe undergoes a rigorous quality inspection process before delivery:

• Ultrasonic Testing (UT): Detects internal defects

• Hydrostatic Pressure Test: Ensures the tube withstands required pressures

• Hardness Testing: Confirms post-heat treatment hardness

• Surface Roughness Check: Confirms Ra ≤ 0.2 μm

• ID and OD Inspection: Ensures H8 tolerance and concentricity

• Length and Straightness: Checked using laser or digital tools

All tubes are supplied with Mill Test Certificates (MTC) and full traceability records.

Packaging & Delivery

To protect your 4140 honed tubes during transport:

• End Caps to prevent internal contamination

• Wrapped in VCI Film or anti-rust paper

• Bundled with Tags showing heat number, size, and batch info

• Optional Wooden Crates for export or long-term storage

• Fast Delivery: Standard sizes in stock; custom orders ship in 7–20 days