A672 C70 steel pipe is a low-alloy high-strength electric fusion welded steel pipe specially used for medium-high temperature and high-pressure pipeline systems. Its core material characteristics are as follows:
1. Basic material properties
Alloy composition positioning
Low-carbon manganese-silicon alloy steel, the carbon content is strictly controlled at ≤0.22% (better than the upper limit of general A672 steel pipe), and the balance of high strength and toughness is achieved by adding manganese (1.00%-1.60%), silicon (0.15%-0.40%) and trace elements such as niobium and vanadium.
Phosphorus and sulfur control: ultra-low impurities (P/S≤0.025%), significantly improving low-temperature brittle fracture resistance.
Core of metallurgical design
Microalloy strengthening: niobium and vanadium elements refine the grains, making the -46℃ impact energy ≥27J (meeting the CL22 low-temperature classification).
Purity guarantee: the vacuum degassing process is used to reduce the gas content and improve the homogeneity of the material.
2. Core Mechanical Properties
| index | Numerical requirements | Performance Advantages |
|---|---|---|
| Yield Strength | ≥485 MPa | The pressure bearing capacity is 40% higher than that of ordinary steel pipes. |
| Tensile Strength | ≥620 MPa | Applicable to high pressure systems above 10MPa |
| Elongation | ≥18% | Support cold bending and welding deformation |
| Low temperature toughness | -46℃ Impact energy ≥27J (CL22) | Polar/Deep Sea Environment Safety Basics |
3. Process and structural characteristics
Manufacturing process
Forming technology: JCOE/UOE progressive pressing process is adopted to avoid excessive deformation of materials;
Welding method: Multi-wire submerged arc welding (SAW) ensures weld penetration and density;
Heat treatment: Normalizing + quenching + tempering (according to some processes) to eliminate welding stress and refine the structure.
4. Typical application scenarios
- Energy field
Supercritical power plant boiler high-pressure feed water pipe (≤480℃/30MPa);
LNG storage tank low-temperature transmission pipeline (-162℃ working condition).
- Chemical and oil and gas
Sulfur-containing oil and gas gathering and transportation pipeline (resistant to H₂S stress corrosion);
Chemical reactor high-pressure circulation system.
