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Inconel 625 (UNS N06625) is a nickel-chromium-molybdenum alloy known for its outstanding strength and corrosion resistance across a broad range of temperatures. Its mechanical properties, particularly yield strength, vary significantly with temperature due to its solid-solution strengthening mechanism. This article examines how yield strength changes with rising temperature and provides tabulated data to help engineers and materials specialists make informed decisions for high-temperature applications.
What is Yield Strength?
Yield strength is the stress at which a material begins to deform plastically. For Inconel 625, the yield strength is particularly important in applications involving heat, pressure, and mechanical load, such as in aerospace, marine, nuclear, and chemical processing industries.
Typical Yield Strength of Inconel 625 at Room Temperature
| Condition | Standard | Yield Strength (0.2% Offset) | Unit |
|---|---|---|---|
| Annealed | ASTM B443 | 276 | MPa |
| Solution-Annealed | AMS 5666 | 275–310 | MPa |
| Hot-Worked | ASTM B446 | ≥276 | MPa |
Inconel 625 Yield Strength vs Temperature
The table below illustrates the approximate yield strength of Inconel 625 across a temperature range from room temperature up to 1000°C.
| Temperature (°C) | Temperature (°F) | Yield Strength (MPa) | Yield Strength (ksi) |
|---|---|---|---|
| 20 | 68 | 276 | 40 |
| 100 | 212 | 265 | 38.4 |
| 200 | 392 | 250 | 36.3 |
| 300 | 572 | 235 | 34.1 |
| 400 | 752 | 220 | 31.9 |
| 500 | 932 | 200 | 29.0 |
| 600 | 1112 | 180 | 26.1 |
| 700 | 1292 | 160 | 23.2 |
| 800 | 1472 | 145 | 21.0 |
| 900 | 1652 | 130 | 18.8 |
| 1000 | 1832 | 115 | 16.7 |
Yield Strength Behavior with Temperature
As seen from the data above, Inconel 625 retains a significant portion of its strength at elevated temperatures. This retention is due to its solid-solution strengthening by molybdenum and niobium. However, like most metals, it shows a consistent decline in yield strength as temperature increases.
Applications Based on High-Temperature Strength
Due to its excellent strength retention, Inconel 625 is widely used in:
| Application Area | Examples | Operating Temperature |
|---|---|---|
| Aerospace | Exhaust systems, jet engines | Up to 800°C |
| Power Generation | Heat recovery boilers | Up to 700°C |
| Marine | Seawater piping | Ambient to 300°C |
| Chemical Processing | Heat exchangers | Up to 500°C |
Frequently Asked Questions
1. What is the yield strength of Inconel 625 at room temperature?
In annealed condition, the yield strength of Inconel 625 at room temperature is typically around 276 MPa (40 ksi).
2. How does temperature affect Inconel 625's yield strength?
As temperature increases, the yield strength of Inconel 625 decreases gradually, but it retains considerable strength even at temperatures up to 1000°C.
3. At what temperature does Inconel 625 lose half of its original yield strength?
Inconel 625 loses approximately 50% of its room temperature yield strength around 700°C (1292°F), where it reaches around 160 MPa (23.2 ksi).