P355QH | Pressure Vessel Steel
P355QH | Pressure Vessel Steel
P355QH is a high-strength carbon steel for pressure vessels and high-temperature use. “P” stands for pressure, “355” indicates a 355 MPa yield strength, and “QH” refers to quenching and tempering. Equivalent grades include P355NH and A516 Grade 70. It offers toughness, weldability, and heat resistance and is used in boilers, pressure vessels, and heat exchangers in the oil, gas, power, and chemical industries.
We provide P355Q/QH products in 12–100mm thicknesses, widths of 900–4800mm, and lengths of 3000–25000mm according to EN 10028-6 standards.
Description
What is P355QH?
P355QH is a carbon steel made of about 98% iron, 0.16-0.18% carbon, 1.10-1.70% manganese, 0.40% silicon, 0.025% phosphorus, and 0.015% sulfur. It’s solid, grey steel, hot-rolled, quenched, and tempered for strength. Known for toughness, weldability, and heat resistance, it’s used in pressure vessels, boilers, and heat exchangers in oil, gas, power, and chemical industries. P355QH is part of quenched and tempered pressure vessel steels, along with P355QL1 and P355QL2.Characteristics of P355QH Steel
Chemical Compositions
| Element | Content (%) |
|---|---|
| Iron, Fe | ~98 |
| Carbon, C | 0.16-0.18 |
| Manganese, Mn | 1.10-1.70 |
| Silicon, Si | ≤ 0.40 |
| Phosphorus, P | ≤ 0.025 |
| Sulfur, S | ≤ 0.015 |
| Chromium, Cr | ≤ 0.30 |
| Molybdenum, Mo | ≤ 0.08 |
Physical Properties
| Physical Property | Metric | Imperial |
|---|---|---|
| Density | 7.85 g/cm³ | 0.284 lb/in³ |
| Melting Point | 1420-1460 °C | 2588-2660 °F |
| Boiling Point | Not available | Not available |
| Thermal Conductivity | 48 W/m·K | 333 BTU·in/(hr·ft²·°F) |
| Electrical Conductivity | ~10 MS/m | ~10 MS/m |
| Specific Heat Capacity | 460 J/kg·K | 0.11 Btu/lb·°F |
| Thermal Expansion Coefficient | 12.0 × 10⁻⁶ /K | 6.67 × 10⁻⁶ /°F |
| Electrical Resistivity | ~0.1 Ω·mm²/m | ~0.1 Ω·mm²/m |
Mechanical Properties
| Mechanical Property | Metric | Imperial |
|---|---|---|
| Tensile Strength | 490-630 MPa | 71.1-91.4 ksi |
| Yield Strength | 355 MPa | 51.5 ksi |
| Brinell Hardness | ~150 HB | ~150 HB |
| Rockwell Hardness | ~80 HRB | ~80 HRB |
| Vickers Hardness | ~160 HV | ~160 HV |
| Elongation | 22-24% | 22-24% |
| Elastic Modulus | 210 GPa | 30,500 ksi |
Data After QT(Quenching and Tempering) Processing
| Mechanical Property (QT) | Metric | Imperial |
|---|---|---|
| Tensile Strength | 550-700 MPa | 79.8-101.5 ksi |
| Yield Strength | 390 MPa | 56.6 ksi |
| Brinell Hardness | ~180 HB | ~180 HB |
| Rockwell Hardness | ~85 HRB | ~85 HRB |
| Vickers Hardness | ~190 HV | ~190 HV |
| Elongation | 20-22% | 20-22% |
| Elastic Modulus | 210 GPa | 30,500 ksi |
Industries & Applications
| Industries | Products |
|---|---|
| Power Generation | Boilers, Steam Drums, Heat Exchangers, Pressure Vessels, Turbines |
| Oil and Gas | Pipeline Systems, Refinery Vessels, Heat Exchangers, Storage Tanks, Separators |
| Chemical Processing | Reactors, Distillation Columns, Pressure Vessels, Heat Exchangers, Storage Tanks |
| Petrochemical Industry | Refinery Equipment, Boilers, Heat Exchangers, Storage Vessels, Pressure Cylinders |
| Manufacturing | Boilers, Pressure Vessels, Industrial Ovens, Heat Treatment Furnaces, Autoclaves |
| Energy and Utilities | Heat Exchangers, Pressure Vessels, Steam Turbines, Storage Tanks, Water Heaters |
Machining
P355QH Heat Treatment
- Normalizing (Optional):
- Heat to 890-950°C (1634-1742°F).
- Hold until fully austenitized, then air cool.
- Effect: Refines grain structure and improves toughness.
- Quenching:
- Heat to 900-950°C (1652-1742°F).
- Hold until fully austenitized, then rapidly cool in water or oil.
- Effect: Increases strength and hardness while refining grain structure.
- Tempering:
- Reheat to 600-680°C (1112-1256°F).
- Hold for a sufficient time, then air cool.
- Effect: Reduces brittleness and improves toughness and ductility.
- Stress Relieving (Optional):
-
- Heat to 550-650°C (1022-1202°F).
- Hold for 1-2 hours, then cool in air.
- Effect: Relieves internal stresses from quenching or forming.
-
P355QH Surface Finish
- Pickling: Removes surface impurities and oxidation for a clean metal surface.
- Galvanizing: Coats the steel with zinc to enhance corrosion resistance.
- Painting: Adds a protective layer to resist corrosion and wear.
- Shot Blasting: Cleans the surface and improves coating adhesion.
- Polishing: Provides a smooth, reflective finish for aesthetic or functional purposes.
- Passivation: Enhances corrosion resistance by forming a protective oxide layer.
Custom surface treatment requirements can be accommodated upon request.
Disclaimer
The above heat treatment instructions and surface finish processing methods for p355qh steel are provided for informational purposes only. Actual results may vary based on specific conditions and equipment used. Testing is recommended, and a metallurgical expert or material supplier should be consulted to ensure the processes are suitable for your specific application. The user assumes all risks and liability for the use of this information.
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