Effect of Room Temperature Fine Particle Peening Pretreatment on Grain Refinement of Fe–Cr Alloys by AIH-FPP

Fine particle peening (FPP) at room temperature was introduced to create finer grains at the surfaces of Fe–Cr alloys that were then treated by atmospheric controlled induction heating FPP (AIH-FPP). The effect of the proposed treatment on the grain refinement behavior of the alloys was investigated using optical microscopy and micro-Vickers hardness testing. The FPP pretreatment at room temperature increased the effectiveness of the grain refinement via dynamic recrystallization during subsequent AIH-FPP. Grain refinement at the surface of Fe–Cr alloys progressed with an increase in the cycles of the treatment. The addition of Cr in Fe–Cr alloys promotes the formation of fine grains during the treatment. Specimens with fine grains created via static recrystallization were also prepared and compared to grains formed via dynamic recrystallization by the room temperature FPP pretreatment and subsequent AIH-FPP to evaluate the effectiveness of the proposed treatment. The grains formed through dynamic recrystallization by the proposed treatment were finer than those formed through static recrystallization. These results indicate that the proposed combination of room temperature FPP and AIH-FPP is effective for the formation of fine grains at the surfaces of Fe–Cr alloys.