Thermal stability of laser shock peening processed Ni-based superalloy DZ17G

Ni-based superalloys are widely used in challenging environments due to their exceptional mechanical properties. To enhance their resistance to damage, surface modification by laser shock pinning (LSP) is an approach to improve performance of superalloys. Considering that superalloys are typically used at high temperatures, the thermal stability of the LSP-processed material should be studied. In this article, the hardness and microstructure of a LSP-processed Ni superalloy, DZ17G, are characterized after annealing at various temperatures (up to 1000 °C) for different time periods. The results show that the majority of the strength increase achieved at the sample surface from LSP processing is lost after annealing at 800 °C for 10 h. Detailed microstructural characterization by synchrotron μXRD and metallography shows that the hardness decrease is due primarily to the annihilation of dislocations, and no recrystallization occurs in the temperature range studied.