Deciphering the deformation mechanism in single point incremental forming: experimental and numerical investigation

In the present work, deformation mechanism in single-point incremental forming (SPIF) of drawing quality steel with a fully ferritic microstructure was studied. The effect of tool diameter and vertical step size on the micromechanisms of plastic deformation in SPIF was investigated by observing changes in microstructure and lattice rotation. It was observed that the fraction of grains with {111} normal direction (ND), which constitutes the gamma fiber in BCC materials, decreased with decrease in tool diameter and vertical step size. It is known that the state of deformation in SPIF is near to plane strain with the direction of major strain being always perpendicular to tool travel direction and negligible strain parallel to tool movement direction. Microstructural evidence for this observation and also for the presence of through thickness shear (TTS) components at smaller step size and tool diameter was observed. Viscoplastic self-consistent (VPSC) simulations revealed that the activity of {112} < 11<(1)over bar> > slip system decreased in comparison to {110} < 1<(1)over bar>1 > slip system in the presence of TTS which manifested as the deviation from {111} parallel to ND position at smaller step size and tool diameter.