Steel Pipe & Tube & Precision Steel Tube,10#、20#、35#、45#、16Mn、20Cr、40Cr、42CrMo
Detailed Description of Precision Steel Tubes
1. Product Definition
Precision steel tubes (also known as precision seamless steel tubes) are high-precision pipes manufactured through cold rolling, cold drawing and finishing processes. They feature no oxide layers on inner and outer walls, and possess far superior dimensional accuracy and surface finish compared with ordinary seamless tubes. They are widely used in working conditions requiring high pressure, tight sealing and precise fitting.
2. Production Process
Round steel → Piercing → Multi-pass cold drawing / cold rolling → Bright annealing → Pickling / Phosphating → Saponification → Straightening → Non-destructive testing → Precision cleaning → Rust-proof packaging
Cold rolling: Adopts three-roll or multi-roll rolling. The outer diameter tolerance can reach ±0.05 mm, with surface roughness Ra ≤ 0.4 μm.
Cold drawing: Processed by multi-pass stretching with uniform wall thickness, ideal for small-diameter and thin-walled tubes.
3. Material Grade & Chemical Composition
Common grades: 10#, 20#, 35#, 45#, 16Mn, 20Cr, 40Cr, 42CrMo, etc.Typical chemical composition (wt%):
| Grade | C | Si | Mn | S ≤ | P ≤ | Cr |
|---|---|---|---|---|---|---|
| 20# | 0.17–0.23 | 0.17–0.37 | 0.35–0.65 | 0.035 | 0.035 | — |
| 45# | 0.42–0.50 | 0.17–0.37 | 0.50–0.80 | 0.035 | 0.035 | — |
| 40Cr | 0.37–0.45 | 0.17–0.37 | 0.50–0.80 | 0.035 | 0.035 | 0.80–1.10 |
4. Specification Parameters
Outer Diameter: 6–168 mm (customized available)
Wall Thickness: 1–30 mm
Length: 5–7 m per piece (fixed length available)
Accuracy Grade:
| Grade | Outer Diameter Tolerance | Wall Thickness Tolerance | Application |
|---|---|---|---|
| Standard Precision | ±0.20 mm | ±5% | Hydraulic systems, precision machinery |
| Ultra-high Precision | ±0.05 mm | ±3% | Aerospace, precision instruments |
5. Core Performance
Dimensional Accuracy: Outer diameter tolerance ±0.05~±0.20 mm, wall thickness tolerance ±3%~±5%.
Surface Quality: No oxide scales or scratches on inner and outer walls, Ra ≤ 0.4 μm for bright finished tubes.
Mechanical Properties: Tensile strength 550–800 MPa, elongation ≥15%. No deformation after cold bending, no cracks during flaring and flattening tests.
Pressure Resistance: Able to withstand high pressure up to 100 MPa without leakage.
Metallographic Structure: Fine grain structure (Grade ≥8) after heat treatment for long fatigue life.
6. Executive Standards
National Standard: GB/T 3639-2020 (Precision Seamless Steel Tubes), GB/T 8713 (Tubes for Cylinder Barrels)
International Standard: DIN 2391-2, ASTM A519, EN 10305-1
7. Application Fields
Hydraulic & Pneumatic Industry: Cylinder barrels, high-pressure oil pipes, servo valve sleeves
Automotive Industry: Brake pipes, shock absorber tubes, steering shaft sleeves
Precision Machinery: Main shaft sleeves, bearing sleeves, guide pillars and guide bushes
Petrochemical Industry: High-pressure instrument tubes, anti-corrosion conveying pipes
Aerospace Industry: Hydraulic pipelines, fuel pipes (light weight and high reliability)
8. Packaging & Delivery
Packaging: Wrapped with moisture-proof and rust-proof film, covered with woven bags or wooden cases. Both ends are capped for dust prevention.
Lead Time: 5–7 days for regular stock items; 7–15 days for customized products.
Quality Documents: Material certificates, non-destructive testing reports and dimensional inspection records are provided, complying with EN 10204 3.1/3.2 certification.
9. Product Advantages
VS Ordinary Seamless Tubes: 5 to 10 times higher dimensional accuracy, 10 times better surface finish, with greatly improved pressure resistance and sealing performance.
VS Welded Tubes: Seamless structure with uniform mechanical properties, superior fatigue resistance and pressure bearing capacity.
10. Purchase Guidelines
Confirm outer diameter, wall thickness, length, material grade and accuracy grade before ordering.
Select ultra-high precision grade (±0.05 mm) with Ra ≤ 0.4 μm for high-pressure and sealing applications.
Require 100% ultrasonic and eddy current testing to eliminate cracks and inclusions.
Material selection recommendation: 20# / 45# for hydraulic parts, 42CrMo for high-strength components.
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