Suppression of Free Surface Roughening of Metal with Plastic Deformation

Abstract

Surface roughening of metals with plastic deformation is governed not only by the strain but also by the crystal grain size of the materials. Therefore surface roughening may be expected to decrease when a material with smaller crystal grains at the surface layer is produced. In the present investigation, a thin layer with small crystal grain size is coated on the surface of an aluminium alloy and the effects of the crystal grain size, as well as the thickness of the surface layer, on surface roughening are evaluated in an upsetting test. It is shown that surface roughening is dominated only by the crystal grain size on the surface layer and so surface roughening can be suppressed by coating the surface of the material with a thin layer of small crystal grains.