Effect of Ultrasonic Shot Peening and Laser Shock Peening on the Microstructure and Microhardness of IN738LC Alloys

IN738LC is a conventional-cast Ni-based superalloy intended for power generation and aerospace applications. Typically, ultrasonic shot peening (USP) and laser shock peening (LSP) are utilized to enhance cracking, creep, and fatigue resistance. In this study, the optimal process parameters for USP and LSP were established by observing the microstructure and measuring the microhardness of the near-surface region of IN738LC alloys. The LSP impact region (modification depth) was approximately 2500 mu m, which was much higher than the USP impact depth of 600 mu m. The observation of the microstructural modification and resulting strengthening mechanism revealed that the build-up of dislocations upon peening with plastic deformation was crucial for alloy strengthening in both methods. In contrast, significant strengthening via gamma ' shearing was observed only in the USP-treated alloys.

Automated summary

This study established the optimal process parameters for ultrasonic shot peening (USP) and laser shock peening (LSP) on IN738LC alloys. The microstructural observations and microhardness measurement revealed that plastic deformation-induced dislocation build-up was crucial for alloy strengthening in both methods, while significant strengthening via gamma ' shearing was only observed in the USP-treated alloys.