Inconel 718 is a staple in high-temperature pitot probe applications, but its mechanical behavior at 1000°C requires careful evaluation to ensure reliable performance in extreme environments like gas turbine exhausts.Gas Pressure Scanwelcome to click on the website to learn more!
At 1000°C, Inconel 718 retains approximately 60% of its room-temperature tensile strength (around 600 MPa vs. 1000 MPa at 25°C), making it suitable for sustained loads in high-heat flow fields. However, creep—slow deformation under constant stress—becomes a critical concern. A 500-hour test at 1000°C with a 100 MPa load showed 0.2% creep strain, which, while minimal, can alter probe hole alignment over time, leading to 1-2% measurement errors.
Oxidation resistance is another key attribute. The alloy forms a dense chromium oxide layer at high temperatures, reducing material loss to less than 0.01mm/year in air. In a jet engine test, an Inconel 718 probe showed negligible weight loss after 1000 hours at 950°C, whereas a 316 stainless steel probe lost 0.15mm of material under the same conditions.
Grain structure plays a role in high-temperature performance. Fine-grained Inconel 718 (grain size ASTM 8-10) offers better creep resistance than coarse-grained variants, as observed in a comparative test where fine-grained probes maintained dimensional stability 30% longer.
For applications exceeding 1000°C, combining Inconel 718 with a ceramic coating (e.g., yttria-stabilized zirconia) extends usability by reducing heat absorption. This hybrid design is common in rocket engine tests, where probe longevity directly impacts data completeness.