Effect of ultrasonic shot peening surface alloying on recrystallisation of a single crystal superalloy

Abstract

Shot peening can greatly enhance the fatigue resistance of single crystal (SX) superalloy, but plastic deformation facilitates the formation of recrystallisation, which will damage the mechanical properties of SX components. In this study, we provide a novel strategy for the surface strengthening without losing or relatively maintaining the integrity of SX by ultrasonic shot peening (USP) surface alloying. An aluminum layer with 10 μm thickness is fabricated on SX substrate compound with surface strengthening treatment. After annealing at 1250 °C, surface recrystallisation is completely inhibited and cellular recrystallisation is significantly reduced in sample processed by USP surface alloying as compared to the sample only subjected to USP. The inhibition effect is attributed to the outstanding oxidation resistance and supplement of Al to the interior by alloying layer, which could enhance the stability of cubic γʹ.