The nanometric control in tool cutting edge sharpness of microtools when micropunching austenitic stainless steel SUS304 was investigated in this study. To achieve stable grain deformation and strain-induced martensitic transformation, an argon ion irradiation beam for finishing the cutting edge of a micropunch of nanometric size was developed. Firstly, micropunching was performed with normal ground tools and ion-polished tools. Secondly, the process affected zones existed in the vicinity of the punched hole were investigated by electron backscatter diffraction (EBSD). Moreover, the effects of differences in the tool cutting edge on grain deformation and strain-induced martensitic deformation were discussed. We found that ion-polished tools can effectively reduce grain deformation and strain-induced transformation.
