p355gh vs p355nl2
Chemical Composition
| Element | P355GH (EN 10028-2) | P355NL2 (EN 10028-3) | Key Differences |
|---|---|---|---|
| Carbon (C) | ≤ 0.18% | ≤ 0.18% | Identical maximum carbon limits, ensuring similar weldability and base strength potential. |
| Silicon (Si) | ≤ 0.60% | ≤ 0.60% | Same silicon limits, providing comparable deoxidation and high-temperature scaling resistance. |
| Manganese (Mn) | 1.10–1.70% | 1.10–1.70% | Identical manganese range, ensuring similar hardenability and strength levels. |
| Phosphorus (P) | ≤ 0.025% | ≤ 0.020% | P355NL2 has a stricter phosphorus limit for improved toughness, especially at low temperatures. |
| Sulfur (S) | ≤ 0.010% | ≤ 0.002% (max, with possible additional restrictions) | P355NL2 has significantly lower sulfur content, drastically reducing the risk of hot cracking and improving cleanliness. |
| Alloying Elements | May contain trace Mo, Nb, V for high-temp strength | May contain controlled Nb, V, Ti, B, and Al for fine-grain structure and enhanced toughness | P355NL2 uses microalloying for superior low-temperature toughness and weldability; P355GH focuses on high-temperature performance. |
| Aluminum (Al) | Not typically specified or controlled | May be added as an deoxidizer and grain refiner | Aluminum in P355NL2 improves cleanliness and toughness. |
Mechanical Properties
| Property | P355GH (EN 10028-2) | P355NL2 (EN 10028-3) | Key Differences |
|---|---|---|---|
| Yield Strength (ReH) | ≥ 355 MPa (thickness ≤ 16mm) | ≥ 355 MPa (thickness ≤ 16mm) | Identical yield strength requirements. |
| Tensile Strength (Rm) | 490–630 MPa | 490–630 MPa | Same tensile strength range. |
| Elongation (A5) | ≥ 20% (thickness ≤ 16mm) | ≥ 22% (longitudinal, thickness ≤ 16mm) | P355NL2 requires slightly better elongation for enhanced ductility. |
| Impact Toughness | ≥ 27 J at 0°C | ≥ 27 J at -50°C | P355NL2 has superior low-temperature toughness, tested at -50°C vs. 0°C for P355GH. |
Key Application-Related Properties
| Property/Application | P355GH | P355NL2 | Key Differences |
|---|---|---|---|
| Heat Treatment | Usually normalized (N) or quenched & tempered | Usually normalized (N) or normalized and tempered (N+T) | Both require heat treatment, but P355NL2 may undergo additional tempering for improved low-temperature toughness. |
| Intended Use | High-pressure vessels, boilers, and moderate-temperature piping | Ultra-low-temperature pressure vessels, cryogenic systems, and extreme environments | **P355NL2 is designed for extremely low-temperature and high-integrity pressure applications; P355GH is for moderate-temperature pressure systems. |
| Weldability | Good, but may require preheating for thick sections | Excellent, with fine-grain structure and low impurities enhancing weld quality | P355NL2's microalloying and ultra-low sulfur significantly improve weldability and reduce cracking risk. |
| High-Temperature Performance | Suitable for temperatures up to ~400°C | Limited high-temperature capability; optimized for low-temperature toughness | P355GH retains strength better at elevated temperatures; P355NL2 focuses on ultra-low-temperature integrity. |
| Low-Temperature Performance | Limited (impact tested at 0°C) | Exceptional (impact tested at -50°C) | P355NL2 is ideal for cryogenic or extreme cold-climate pressure applications. |
| Creep Resistance | Moderate, due to potential microalloying | Enhanced due to fine-grain structure and microalloying | P355NL2 may offer better long-term stability under stress at ultra-low temperatures. |
| Standard Reference | EN 10028-2 (pressure vessel steel) | EN 10028-3 (fine-grain, low-temperature pressure vessel steel) | Different standards reflecting distinct design philosophies: P355GH for general pressure; P355NL2 for ultra-low-temperature/high-integrity systems. |
