Formation Of Surface Nanocrystalline Structure In Steels By Air Blast Shot Peening

Author:  H. Saitoh, T. Ochi, M. Kubota
Source:  Conf Proc: ICSP-10 Tokyo, Japan 2008
Doc ID:  2008115
Year of Publication:  2008
ABSTRACT The influences of steel hardness and shot peening (SP) conditions on the surface nanocrystalline layers produced by air blast SP was investigated with steels having Vickers hardness ranging from 260HV to 710HV. It was found that the easiness to form a nanocrystalline structure is related to steel hardness and SP conditions. Considering geometrically necessary (GN) dislocation density at surface of steel after SP, it can be said that the greater GN dislocation density at surface, the greater the amount of nanocrystalline layers and there is a critical GN dislocation density to form a nanocrystalline structure. The experimental results seem to support the dynamic continuous recrystallization mechanism rather than dynamic phase transformation mechanism. KEY WORDS shot peening, nanocrystalline structure, steel, surface, dislocation

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