In single point incremental forming of 304 austenitic stainless steel, the effects of the tool rotation rate on the forming limit, surface appearance, forming shape, martensite fraction, and microstructure were evaluated. When the tool rotation rate was relatively low, forming limit was drastically reduced with increasing tool rotation rate owing to intermittent swarf-like flash formation at the tool-contact surface. The amount of martensite formed increased with decreasing tool rotation rate or increasing elongation of the sheet. The evolution of the deformation microstructure and texture was similar to that in rolling. On the other hand, in the case of a relatively high rotation rate, the forming limit was improved with increasing tool rotation rate owing to continuous friction stirring and heating at the tool-contact surface. The forming accuracy was improved compared with that obtained with a low rotation rate.
