抄録
The formation of nanocrystalline (NC) structure in steels by ball milling, shot peening and drilling were. Studied. The NC structure with equiaxed ferrite grains of 20 nm formed with boundaries from deformed structure regions by these methods. The NC layers showed extremely higher hardness, than that of deformed structure regions. By annealing, the NS layers showed substantially slow grain growth without recrystallization. The temperature of specimens during ball milling and shot peening was low and deformation was done in ferrite state. While, in drilling the microstructure indicated that the temperature of drill hole surface region was above A,3 and the NC structure formed in austenite condition. It is recognized that NC structure formed by these methods has similar characteristics irrespective of the deformation temperature.
