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Help CenterSteel Pipe & Tube & Precision Seamless Steel Pipe，10#、20#、45#、Q345(16Mn)、40Cr、42CrMo、15CrMo、35CrMo
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Precision Seamless Steel Tube Product Specification
1. Product Overview
Precision seamless bright steel tube is manufactured from high-quality round steel billet via multi-pass cold rolling / cold drawing plus bright annealing finishing process. Different from ordinary hot-rolled seamless pipes, it features tight dimensional tolerance, ultra-smooth inner surface, oxide-free surface, excellent pressure resistance without leakage, and no cracking during cold bending, flaring or flattening. The tube can be directly processed and assembled without secondary turning or boring, widely used as core raw material for hydraulic & pneumatic components, automobile parts and precision machinery.
Applicable Standards
Domestic Standard: GB/T3639-2020 (Cold-drawn Precision Seamless Steel Pipe), GB/T8713 (Hydraulic & Pneumatic Precision Tube), GB/T8162 (Structural Pipe), GB/T8163 (Fluid Conveyance Pipe)
International Standard: DIN2391-2 (German Standard), EN10305 (European Standard), ASTM A519/A179 (American Standard), JIS G3459 (Japanese Standard)
2. Common Grades & Chemical Composition
2.1 Carbon Steel Series (In Stock Regularly)
| Grade | C | Si | Mn | S(max) | P(max) | Application |
|---|---|---|---|---|---|---|
| 10# | 0.07~0.13 | 0.17~0.37 | 0.35~0.65 | 0.035 | 0.035 | Thin-wall instrument tube, low-pressure fluid pipe, bending parts |
| 20# | 0.17~0.23 | 0.17~0.37 | 0.35~0.65 | 0.035 | 0.035 | Hydraulic cylinder barrel, auto shock absorber tube (Most widely used) |
| 45# | 0.42~0.50 | 0.17~0.37 | 0.50~0.80 | 0.035 | 0.035 | Wear-resistant shaft sleeve, high-strength precision machined parts |
| Q345(16Mn) | 0.12~0.20 | 0.20~0.55 | 1.20~1.60 | 0.035 | 0.035 | Heavy-load hydraulic pipeline for construction machinery |
2.2 Alloy Steel Series (Custom for High Strength)
Including 40Cr, 42CrMo, 15CrMo, 35CrMo, 4130(ASTM), 42CrMo4(DIN). Features high temperature resistance, wear resistance and fatigue resistance, applied for heavy-duty truck transmission shaft, high-pressure hydraulic system and petrochemical instrument tube.
3. Technical Specifications
Outer Diameter (OD): φ6mm～φ219mm, regular stock range φ8~120mm, special oversized/undersized sizes available upon custom order
Wall Thickness (WT): 0.5mm～20mm; thin wall:0.5~3mm, medium & heavy wall:3~20mm
Standard Length: 6m per piece, customizable length from 4m to12m with length tolerance ±5mm; short cut available
Dimensional Tolerance
OD tolerance: ±0.05~±0.10mm normally (ordinary seamless pipe ±0.5~1.0mm), ultra-precision up to ±0.03mm
WT tolerance: ±5%~±10%
Inner surface roughness: Ra≤0.4~1.6μm, oxide-free bright finish
Straightness: ≤0.3mm/m, ovality ≤0.05mm
4. Production Process
Round Steel Billet → Hot Piercing into Hollow Shell → Pickling, Phosphating & Saponification → Multi-pass Cold Rolling/Cold Drawing → Bright Annealing under Non-oxidizing Atmosphere (NBK/+N) → Straightening → Fixed-length Cutting → Eddy Current Non-destructive Testing → Inner & Outer Surface Cleaning → Anti-rust Oil Coating → Packing & Warehousing
NBK Condition: Normalized bright annealing to eliminate internal stress, excellent ductility and no deformation after cold bending, standard delivery status for hydraulic tubes.
5. Mechanical & Processing Performance
Mechanical Property: Tensile Strength 450~820MPa, Elongation ≥15%; 20# tube withstands ≥80MPa hydraulic pressure without leakage, 42CrMo up to over120MPa
Machinability: No crack after 90° cold bending, qualified for flaring & flattening test; available for turning, boring, galvanizing and honing; clean inner wall reduces hydraulic fluid flow loss
Surface Options: Natural bright finish, phosphating, electro-galvanizing (zinc coating 8~12μm), honed cylinder tube, black oxide finish
6. Product Classification
DIN2391/C Hydraulic Precision Tube: Honed tube & cylinder barrel with inner Ra≤0.4μm for hydraulic & pneumatic cylinder
Cold-drawn Precision Tube: Small-bore thin-wall pipe, flexible non-standard dimension for instrument and precision spare parts
Cold-rolled Bright Precision Tube: High precision mass production for auto brake pipe & shock absorber sleeve
Alloy Precision Tube: High temperature & high pressure service for boiler instrument and petrochemical high-pressure pipeline
7. Application Fields
Hydraulic & Pneumatic Industry: Cylinder barrel, high-pressure hydraulic tubing, servo valve sleeve
Automobile Manufacturing: Shock absorber tube, steering sleeve, brake pipe, transmission shaft casing
Precision Machinery & Robot: Guide sleeve, machine tool spindle casing, bearing bush, linear guide pipe
Petrochemical Instrument: High-pressure impulse tube for instrumentation
Construction & Agricultural Machinery: Hydraulic pipeline and heavy-load structural components
General Equipment: Precision pipeline for air compressor and refrigeration equipment
8. Packing, Lead Time & After-sale Terms
Packing: Small tubes bundled with moisture-proof woven bag, large tubes with single anti-rust oil coating; pallet packing for sea freight, suitable for 20GP container loading (25 tons per container)
Lead Time: In-stock items shipped within 5~7 working days; special grade or non-standard size 7~15 working days
Quality Inspection: Mill Test Certificate provided per batch, full dimensional inspection + eddy current test before delivery, third-party inspection acceptable
Payment Term for Export: 30% TT Advance Payment + 70% Balance before shipment
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