Effect of heat treatment atmosphere on surface recrystallization of a directionally solidified Ni-base superalloy

The effect of heat treatment atmosphere on surface recrystallization (RX) induced by shot-peening in a directionally solidified (DS) superalloy was investigated. The evolution of surface RX and oxidation during heat treatment at 1220 °C in air was revealed by quenching experiments. The RX depth of samples heat treated in air was apparently larger than those heat treated in vacuum. The mechanism was discussed based on the observation of kinetics of oxidation and RX and interactions between them.