Grain Size Refinement of Alloy 617

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Student Presentation

Presentation Date


Faculty Sponsor

Chad Watson


Alloy 617, a nickel-based solid solution alloy, is a frontrunner for use in intermediate heat exchangers (IHXs) as part of the Next Generation Nuclear Plant (NGNP) project. The IHX will be operating at temperatures approaching 1,000˚C for extended durations. At these temperatures, Alloy 617 is susceptible to dislocation creep. However, diffusion creep may also become activated as the grain size of Alloy 617 decreases. Thus, the goal for Idaho National Laboratory is to evaluate the effect of grain size on creep behavior in Alloy 617. In support of this goal, the grain size of Alloy 617 has been refined from 150 µm to between 6 and 40 µm through the use of a thermo-mechanical process. Homologous temperatures were used for determining the heat treatment temperature range, which varied from 300 to 1000°C. With a 50% cold work, the recrystallization zone for Alloy 617 has been established between 800 and 1000°C. The process to recrystallize Alloy 617 will be provided to Idaho National Laboratory for developing a creep relationship as a function of grain size.

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