15Mo3 (designation 1.5415) is a low-alloy heat-resistant steel widely used in high-temperature and high-pressure environments, such as boilers, pressure vessels, and pipelines. Renowned for its excellent creep resistance, weldability, and thermal stability, 15Mo3 is a critical material in energy, petrochemical, and industrial sectors. This article provides a detailed analysis of its standards, composition, performance, applications, and key considerations for manufacturing.
1. Material Standards and Classification
15Mo3 complies with EN 10028-2 (European standard for pressure vessel steels) and is classified as a low-alloy pearlitic heat-resistant steel. Key global standards include:
China: GB/T 5310 (high-pressure boiler tubes), GB/T 8162 (structural pipes).
Germany: DIN 17175 (steel tubes for boilers and pressure vessels).
USA: ASME SA210 (boiler tubes), ASME SA213 (heat exchanger tubes).
2. Chemical Composition
The alloy’s performance is driven by molybdenum (Mo), which enhances high-temperature strength. Its composition is tightly controlled:
| Element | C | Si | Mn | Mo | P≤ | S≤ |
|---|---|---|---|---|---|---|
| Content | 0.12–0.20 | 0.10–0.35 | 0.40–0.90 | 0.25–0.35 | 0.025 | 0.010 |
Key Roles:
Molybdenum (Mo): Improves creep resistance and stabilizes carbides at elevated temperatures.
Carbon (C): Balances strength and weldability; excessive carbon reduces ductility.
3. Key Properties
High-Temperature Performance
Operating Range: Long-term service up to 550°C; short-term exposure to 600°C.
Maintains tensile strength and avoids softening under thermal stress.
Creep Resistance
Withstands deformation under prolonged stress (e.g., boiler tubes in power plants).
Weldability
Preheating (150–250°C) and post-weld heat treatment (PWHT) are recommended.
Compatible with TIG/MIG welding using E9015-B3 electrodes or ER90S-B3 filler wires.
Oxidation Resistance
Forms a protective Fe₃O₄ layer to slow oxidation in steam or flue gas environments.
Mechanical Properties (per DIN 17175):
Tensile Strength: 450–600 MPa
Yield Strength: ≥270 MPa
Elongation: ≥22%
4. Applications
15Mo3 is ideal for components exposed to cyclic thermal loads and pressure:
Power Plants: Superheater tubes, reheater coils, and steam pipelines.
Petrochemical: Reactors, distillation columns, and catalytic cracking units.
Industrial Piping: High-temperature gas/oil transmission lines.
Pressure Vessels: Heat exchangers and synthesis towers (ASME Section VIII compliant).
5. Manufacturing and Processing
Forming:
Hot Working: Performed at 900–950°C; avoid temperatures below 850°C during rolling.
Cold Working: Requires annealing (650–700°C) to relieve stress.
Heat Treatment:
Normalizing: 890–950°C followed by air cooling.
Welding Guidelines:
Preheat to 150–250°C to prevent cracking.
Post-weld tempering at 600–650°C enhances toughness.
6. Comparison with Similar Materials
| Material | Advantages | Limitations |
|---|---|---|
| 15Mo3 | Cost-effective, high creep strength | Limited corrosion resistance |
| Carbon Steel | Low cost, easy machining | Max. service temp. ≤400°C |
| 304 Stainless | Superior corrosion resistance | Weak high-temperature strength |
| 12Cr1MoV | Better performance above 600°C | Complex welding requirements |
7. Critical Considerations
Temperature Limits: Prolonged use above 550°C may cause graphitization, reducing ductility.
Corrosion Protection: Coatings or aluminizing are advised for sulfur-containing environments.
Inspection: Monitor welds and bends for creep damage during maintenance.
Conclusion
15Mo3 is a versatile and economical choice for medium-temperature (450–550°C) pressure equipment. Its balanced properties—combining strength, weldability, and thermal stability—make it indispensable in power generation, oil refining, and heavy industry. Proper material selection, adherence to welding protocols, and regular maintenance ensure optimal performance and safety in demanding applications.
Just like you, 70% customers choose long-term cooperation with BBN steel not only for our good product and service quality, good reputation in the international market, but also for our experienced one-stop raw material supply and further steel processing!
