Effects of strain localization on surface roughening during sheet forming

Numerical simulations of evolving surface roughening in sheet have been preformed to determine the influence of microstructure and mechanical properties. The model accounts for the grain structure near the sheet surface with the behavior of the grains being characterized by a constitutive model which accounts for deformation by crystallographic slip and for rotation of the crystal lattice with deformation. In addition to the known linear dependence of surface roughening on strain and grain size, it was determined that small scale strain localization at the surface plays a significant role. Consequently, factors which affect strain localization, such as strain hardening, crystallographic texture and material homogeneity, also affect surface roughening. The results also show patterning of the strain localization which is induced by the material inhomogeneity inherent in a polycrystal.