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27SiMn Q+T Bored Tube

The Q+T process refines the grain structure and enhances the uniformity of mechanical properties, ensuring excellent performance under high pressure and heavy load. The inner bore is precisely machined to achieve smooth surface roughness (Ra ≤ 0.4 μm) and accurate dimensional tolerance, making it ideal for large-diameter hydraulic cylinders.
EASTAI’s 27SiMn Bored Tubes are widely applied in excavators, loaders, mining trucks, metallurgical presses, and other heavy machinery. Custom sizes, lengths, and machining options are available to meet specific engineering requirements.
Choose EASTAI for consistent quality, strict inspection, and reliable supply of high-strength bored tubes that perform stably in the most demanding industrial conditions.

  • Model:Bored Tube

  • Brand:EAST AI

  • Material:27SiMn

Product Description

EASTAI’s 27SiMn Q+T Bored Tube is a high-strength seamless steel tube specially processed through quenching and tempering (Q+T) and precision boring.This tube is widely applied in heavy-duty hydraulic cylinders, construction machinery, mining equipment, and offshore hydraulic systems, where superior strength, toughness, and fatigue resistance are essential.

The 27SiMn steel is well-known for its excellent mechanical properties after heat treatment, combining high tensile strength, impact resistance, and ductility, making it ideal for high-pressure, high-load hydraulic applications.


Applications

Bored tubes are widely used in hydraulic and mechanical industries where high precision and strong load-bearing capacity are required. They are commonly applied in hydraulic cylinder barrels, pneumatic cylinders, engineering machinery, mining equipment, agricultural machinery, lifting platforms, and oilfield machinery. With excellent dimensional accuracy and surface finish, bored tubes ensure smooth piston movement, reduce friction, and extend the service life of hydraulic systems. They are also suitable for manufacturing mechanical sleeves, precision structural parts, and heavy-duty machine components.



Technical Specifications

Item

Details

Material Grade

27SiMn (GB/T 3077)

Condition

Quenched + Tempered (Q+T)

Outer Diameter

80 mm – 800 mm

Wall Thickness

10 mm – 100 mm

Length

up to 12 meters

Surface Finish

Hot Rolled + Bored (custom honed or SRB available)

Inner Diameter Tolerance

±0.3 mm

Straightness

≤ 0.5 mm/m

Surface Roughness (Ra)

≤ 3.2 μm (after boring)

Delivery Standard

GB / ASTM / DIN / EN

Main Features & Advantages

  1. High Strength After Heat Treatment (Q+T)The 27SiMn steel is quenched and tempered to achieve a tensile strength of 850–1000 MPa and yield strength above 600 MPa, providing outstanding load-bearing performance for large hydraulic cylinders.

  2. Excellent Impact & Fatigue ResistanceWith superior toughness and low-temperature impact strength, 27SiMn Bored Tube performs reliably in demanding environments such as mining and marine applications.

  3. Precision Boring ProcessThe inner bore is processed with advanced boring machines to ensure high dimensional accuracy, smoothness, and perfect concentricity — ready for honing or roller burnishing.

  4. Stable Structure & High MachinabilityThe Q+T process refines the microstructure, enhancing dimensional stability and making it suitable for secondary machining (welding, threading, port cutting).

  5. Large Diameter CapabilityEASTAI can supply extra-large bored tubes up to 800 mm OD, providing strong support for large hydraulic systems.

  6. Custom Processing OptionsOptional honing, skiving & roller burnishing, or chrome plating are available according to customer requirements.


Manufacturing Process

  1. Raw Material Selection — High-quality 27SiMn seamless steel tube

  2. Rough Machining & Cutting — Prepare tube blanks to required sizes

  3. Quenching & Tempering (Q+T) — Heat treatment for strength and toughness

  4. Boring Process — Precision boring to reach target ID and wall thickness

  5. Straightening & Finishing — Achieve optimal straightness and roundness

  6. Inspection & Testing — Check mechanical properties, dimensions, and internal defects

  7. Surface Protection — Apply anti-rust oil and end caps before packaging



Quality Control

EASTAI ensures every 27SiMn Q+T Bored Tube meets strict international standards:

  • Dimensional accuracy check (ID, OD, wall thickness)

  • Ultrasonic Testing (UT) for internal defects

  • Mechanical tests (tensile, yield, impact)

  • Hardness inspection (HB 260–290 typical)

  • Hydraulic pressure testing upon request

  • Certificates: ISO 9001:2015, GL AMM, MTC EN 10204 3.1

  • Third-party inspection: SGS / BV / TÜV available




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