Possibility of Applying Superplastic Forging to the Microforming of SUS304

The microforming of SUS304 stainless steel with fine grain structures is carried out utilizing superplastic phenomenon. The configurations of superplastic-formed structures are studied, and possibility of superplastic microforming with SUS304 stainless steel is discussed. The microforming utilizing superplastic phenomenon successfully achieved the formation of pyramid-shaped projection with 50 μm base and 10 μm height on SUS304 specimen with ultra-fine grain structure averaging to 250 nm. It is believed that the surface roughness of the micronsized structure, obtained in this experiment, may have reached below the Rayleigh limit for light with wavelength of at least 2 μm where the surface becomes smooth enough for infra-red (IR) device applications.