Severe plastic deformation by incremental bulk metal forming

Incremental bulk forming technologies are investigated with respect to the creation of ultrafine-grained aluminium material. Based on first investigations of spin extrusion the technology of gradation rolling for rod shaped billets was developed. High strain generation as precondition for grain refinement is caused by the so called knead effect during processing in incremental rolling. Cross sections of processed billets show a demarcated area of different reflexion behaviour and a corresponding increase in hardness. In this area a gradient with decreasing grain size in surface direction is shown by crystallographic mapping. A several millimetre thick layer of refined material has been obtained. © 2010 German Academic Society for Production Engineering (WGP).