RESIDUAL STRESS AND TEXTURE DUE TO COLD AND HOT EXTRUSION PROCESSES

The residual stress state and the texture of cold forward extruded full and hollow steel bodies as well as a hot extruded AlSi25Cu4Mg1 tube are studied by X-ray, high energy synchrotron and neutron diffraction. The experimental results reveal that all samples are fibre textured and that there are characteristic distributions of the residual stresses vs. sample diameter. In case of the cold forward extruded samples at low degrees of natural strain, the rod kernel is under compressive residual stresses which are balanced by tensile residual stresses in the outer part of the sample. In contrast to this, the outer part of the hot extruded sample is under compressive macroscopic stresses which are balanced by tensile macroscopic residual stresses in the inner part of the sample.