1. Medium-High Temperature Range (700℃–950℃)
| Material | Maximum Service Temperature | Features | Applications | Cost-Performance Advantage |
|---|---|---|---|---|
| Inconel 718 (UNS N07718) | Long-term ~700℃, short-term up to 950℃ | Excellent creep and fatigue resistance, good weldability and machinability | Aircraft engine blades, gas turbine components, nuclear reactor parts | Balanced overall performance, widely available, low processing cost |
| GH4169 (Domestic equivalent of Inconel 718) | Long-term 650℃ | Performance comparable to Inconel 718 | Aerospace fasteners, oil drilling tools | Preferred domestic alternative, 20%-30% lower cost, suitable for budget-limited but high-performance requirements |
2. High Temperature Range (950℃–1150℃)
| Material | Maximum Service Temperature | Features | Applications | Cost-Performance Advantage |
|---|---|---|---|---|
| Haynes 230 (UNS N06230) | 1150℃ (oxidizing environment) | Excellent oxidation and thermal corrosion resistance, tungsten and molybdenum strengthened, high-temperature strength | Industrial furnace radiant tubes, chemical cracking furnaces | Long service life design, low maintenance cost, suitable for long-term high-temperature operation |
| GH3230 (Domestic equivalent of Haynes 230) | 1100℃ | Performance close to Haynes 230, AMS5891 certified | Aircraft engine combustion chambers, high-temperature heat treatment fixtures | Domestic alternative, 30%-40% lower cost than import, short delivery time |
3. Ultra-High Temperature Range (>1200℃)
| Material | Maximum Service Temperature | Features | Applications | Cost-Performance Advantage |
|---|---|---|---|---|
| Inconel 740H (UNS N07740) | Short-term 1300℃, long-term 750℃ | Designed for ultra-supercritical power plants, excellent resistance to coal ash corrosion | Boiler superheaters, nuclear power steam pipelines | Suitable for extreme environments, reduces downtime and maintenance, optimal life-cycle cost |
| K418 (Nickel-based casting alloy) | Long-term 1000℃ | Excellent casting properties, suitable for complex parts | Turbine blades, automotive turbochargers | Casting process reduces cost, ideal for batch production |
Cost-Performance Recommendations
| Application Scenario | Recommended Alloy | Reason |
|---|---|---|
| Standard high-temperature parts (≤700℃) | GH4169 | Mature domestic alternative, low cost and reliable performance |
| Industrial furnace / petrochemical equipment (≤1150℃) | GH3230 | Strong oxidation resistance, only 60% of imported Haynes 230 cost |
| Key aerospace engine components | Inconel 718 | Internationally recognized, stable supply chain, extensive long-term usage data |
| Ultra-supercritical power plant extreme environments | Inconel 740H | Only alloy certified under ASME Code Case 2702, optimal life-cycle cost |
| Low-cost cast parts | K418 | Simplified casting process, suitable for small to medium batch production |
Alloy Selection Tips
Clarify temperature requirements: Long-term operating temperature is more important than peak temperature; avoid over-specifying expensive materials.
Consider processing costs: Casting alloys (e.g., K418) are suitable for complex parts; wrought alloys (e.g., GH3230) are better for plates/tubes.
Domestic substitution trend: GH-series alloys now approach international performance, with obvious price advantages (e.g., GH3230 is 30%+ cheaper than Haynes 230).
Long-term maintenance cost: High initial cost alloys (e.g., Haynes 230) may result in lower total cost due to longer service life.
