27SiMn Q+T Bored Tube

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 Resistance
   With superior toughness and low-temperature impact strength, 27SiMn Bored Tube performs reliably in demanding environments such as mining and marine applications.

3. Precision Boring Process
   The 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 Machinability
   The Q+T process refines the microstructure, enhancing dimensional stability and making it suitable for secondary machining (welding, threading, port cutting).

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

6. Custom Processing Options
   Optional 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

Why Choose EASTAI

Over 20 years of hydraulic cylinder material production experience
Advanced Q+T and boring equipment for precision and consistency
10,000+ tons of regular inventory for fast shipment
Custom machining services: boring, honing, SRB, chrome plating
Reliable after-sales support and technical consultation
Proven quality in global hydraulic cylinder OEM supply