Overheating of Waspaloy: Effect of cooling rate on flow stress behavior

In-Situ Monitoring of Phase Transition and Microstructure Evolution in Ni-Based Superalloys by Electrical Resistivity: Direct Comparison With Differential Scanning Calorimetry and Application to Case Studies

“…[45] Because of the high electrical current density (especially at temperatures above 1200 °C), thermal electric voltage can be influenced easily, and this may cause an inaccurate temperature reading up to ± 25 K. Additionally, two Pt (99.99 pct) wires were used to measure the electrical potential difference instead of alumel (Ni-2Al-2Mn-1Si) wires used in the previous study. [34] Because all the tests were performed in air, Pt wires were chosen for better oxidation resistance and durability at very high temperature above 1200 °C. All wires used in this study have 0.125 mm diameter and were supplied by Goodfellow as qualified thermocouple wires.…”

“…The thermal strain was measured by digital image correlation (DIC) using an iMetrum non-contact video extensometry system with VideoGauge software, which was used in previous studies. [34,46] VHT flame proof high temperature spray paint was used to apply speckle patterns on the sample surface to track the thermal strain. This video extensometry setup can measure the specimen's strain up to 1100 °C due to the temperature capability of the paint and incandescence.…”

“…This carbide dissolution is in good agreement with the previous study reporting grain boundary cavitation after overheating at 1000 °C. [34] Like Waspaloy, AD730Ò (Figure 6(b)) also has DSC peaks corresponding to dissolution of M 23 C 6 and c¢ phases at 1042 °C and 1112 °C, respectively. The solvus temperature of M 23 C 6 was identified as a small kink during decreasing resistivity at 1008 °C and that of c¢ is the peak shown at 1107 °C in the resistivity curve.…”

“…[22,23,25,[29][30][31][32][33] Other studies directly compared DSC and resistivity for analyses of physical properties, but data on superalloys are particularly limited. [19][20][21]34,35] Overall, the analyses so far have been limited to specific and fundamental uses, and there is a need for comprehensive understanding to make the best use of this method.…”

“…In this way, it is shown that measurement and analysis of resistivity changes helps to understand a material's state in a non-destructive way. [34] Finally, three different case specific experiments that take advantage of in-situ resistivity measurement are presented and discussed to illustrate how the results can be used to interpret microstructural evolution.…”