LSAW Carbon Steel Pipe DN600

Chemical Composition – Carbon Content Defines Performance

The primary distinction between carbon steel and iron lies in their carbon content, which directly dictates strength, ductility, and weldability-three critical factors for pipe production.

Pure Iron: Low or Excessive Carbon, Inherent Limitations

Pure iron exists in two industrial forms, both unsuitable for pipe manufacturing:

Wrought Iron: Carbon content <0.008%, with trace amounts of slag. It is malleable but weak, with tensile strength of only 200MPa-250MPa-insufficient to withstand even low-pressure fluid transport (≥0.6MPa);

Cast Iron: Carbon content 2%-4%, plus 1%-3% silicon. It is hard but extremely brittle, with impact resistance ≤10J at 20℃-prone to cracking during forming or installation.

Huayang's material testing lab confirms these flaws: cast iron samples shatter when bent 15°, while wrought iron deforms permanently under 1.0MPa pressure. For these reasons, we never use pure iron in pipe production-it cannot meet the durability or safety standards required for infrastructure.

Carbon Steel: Optimized Carbon for Balanced Performance

Carbon steel contains 0.05%-2.06% carbon, a range carefully calibrated to balance strength, ductility, and weldability. At Huayang, we select carbon steel grades based on pipe application:

Low-Carbon Steel (Q235): 0.12%-0.22% carbon, tensile strength 375MPa-500MPa. Used for ERW-made pipes (e.g., Φ25×2.77mm for residential water supply), as it bends easily and welds seamlessly;

Medium-Carbon Steel (Q345): 0.16%-0.20% carbon, tensile strength 470MPa-630MPa. Ideal for HFW steel pipes (e.g., Φ108×4.5mm for industrial process lines), as it withstands higher pressure (up to 3.0MPa);

High-Carbon Steel (API 5L X65): 0.18%-0.23% carbon, tensile strength 535MPa-725MPa. Reserved for high-pressure HFW pipes (e.g., Φ114×8.56mm for oil transmission), as it retains toughness at -40℃.

This optimized carbon content allows our pipes to meet diverse needs: our Q235 ERW pipes handle 1.6MPa residential water pressure, while API 5L X65 HFW pipes withstand 4.0MPa crude oil transport-performance pure iron cannot match.