LAUSR

In the upsetting process, flow of metal starts from centre region to outer region and failure occurs due to nucleation of void, growth of void and finally void coalescence into micro-crack. These micro-cracks extend in the hoop direction and fracture occurs at the equatorial region due to the presence of accumulated stresses. Hence, the failure of the components strongly depends on the stress accumulated on the failure zone. In the present work, the failure zone was identified through upsetting experiments on powder metallurgical Al–4 wt% Ti composites that have different initial relative densities and an aspect ratio of 1. It was found that the failure occurs at the equatorial region due to accumulation of maximum principal stresses. These accumulated stresses affect the failure limit of the work piece during cold upsetting. Hence, it is necessary to relieve these accumulated stresses for better failure limit in various engineering applications. Thus, this work is aimed at relieving the accumulated stresses on the failure zone by heating selectively on the region where more work hardening has taken place during the deformation stage. As the heating has been performed only at selected locations, the mechanical properties of the samples are not expected to deteriorate due to the heating step. As a result, initiation and progression of failure can be delayed by selective heating before the onset of failure initiation. Selective heating relieve the accumulated stresses and delay the failure onset, thereby increasing the failure limit of the metal.