GB/T8162 Seamless Steel Pipe Product Overview
GB/T8162 Seamless Pipes are cold-drawn/hot-rolled carbon/alloy steel tubes designed for mechanical structures, hydraulic cylinders, and low/medium-pressure fluid systems. Compliant with GB/T 8162-2008, these pipes offer 335–590 MPa tensile strength across grades like 20#, 45#, and 15CrMo. With OD tolerances of ±0.50 mm and wall concentricity ≤8%, they replace ASTM A106/API 5L in non-corrosive industrial applications like automotive axles, conveyor rollers, and CNC machinery frames.
Key Technical Specifications
1. Dimensional & Manufacturing Properties
- Size Range:
- Cold-Drawn: 6 mm (¼”) – 426 mm (16″) OD | Wall Thickness: 1.25–40 mm
- Hot-Rolled: 426 mm – 1,016 mm (40″) OD | Wall Thickness: 10–50 mm
- Tolerances:
- OD: ±0.5% (cold-drawn), ±1.0% (hot-rolled)
- Straightness: ≤1.5 mm/m
- Surface Treatments:
- Phosphated: 5–15 µm coating for improved paint adhesion
- Cold-Drawn Bright: Ra ≤0.8 µm for precision hydraulic systems
2. Mechanical & Chemical Performance
Chemical Composition (Key Grades):
| Grade | C | Mn | Cr | Mo | Yield/Tensile Ratio |
|---|---|---|---|---|---|
| 20# | 0.17–0.24% | 0.35–0.65% | ≤0.25% | – | 0.63 |
| 45# | 0.42–0.50% | 0.50–0.80% | ≤0.25% | – | 0.57 |
| 15CrMo | 0.12–0.18% | 0.40–0.70% | 0.80–1.10% | 0.40–0.55% | 0.67 |
Mechanical Properties:
| Grade | Tensile (MPa) | Yield (MPa) | Elongation (%) | Hardness (HB) |
|---|---|---|---|---|
| 20# | 390 | 245 | ≥20 | ≤156 |
| 45# | 590 | 335 | ≥14 | ≤217 |
| 15CrMo | 440 | 295 | ≥22 | ≤201 |
Pressure Ratings:
| OD (mm) | Grade 20# Wall (mm) | Max Pressure @ 20°C (bar) | Burst Strength (bar) |
|---|---|---|---|
| 60.3 | 5.0 | 210 | 630 |
| 168 | 12.0 | 185 | 555 |
Applications by Industry
| Industry | Use Case | Grade | Key Benefit |
|---|---|---|---|
| Automotive | Gearbox shafts, steering columns | 45# | 590 MPa tensile handles 8,000 RPM torque |
| Hydraulics | Cylinder barrels, valve bodies | 20# + Phosphated | ±0.1 mm ID precision |
| Power Plants | Boiler non-pressure tubing | 15CrMo | 540°C oxidation resistance |
| Textile Machinery | Spinning machine rollers | 16Mn | 30% cost savings vs. ST52 |
Global Standard Equivalents
| China (GB) | USA (ASTM) | Europe (EN) | Japan (JIS) |
|---|---|---|---|
| 20# | AISI 1020 | EN 10297-1 C22E | STKM 12A |
| 45# | AISI 1045 | EN 10297-1 C45E | STKM 25C |
| 15CrMo | ASTM A335 P11 | EN 10216-2 13CrMo4-5 | STPA 24 |
Certifications & Compliance
- Heat Treatment: GB/T 13306 (Normalizing at 860–890°C)
- Non-Destructive Testing: UT (GB/T 5777), Eddy Current (GB/T 7735)
- Certifications: ISO 9001, RoHS, REACH
Packing And Delivery
