Evaluation of residual stress effects by means of material removal

Abstract

The residual stresses imposed during the manufacturing process of a component are one of the main potential carriers for the appearance of distortion. In this work experiments concerning dimensional changes of bars after material removal were carried out in order to estimate the residual stress level stored as a consequence of the manufacturing route. The material removal was accomplished after each processing step. The samples were taken after five different steps of a combined colddrawing: pre-straightening, shot-blasting, cold-drawing, straightening and polishing by crossed rolls. The last step was varied according to the angles between crossed rolls: 16°, 17° and 18°. The material removal was accomplished in such a way to leave a material portion corresponding to a depth of 1/6 or 1/2 of the diameter of the bar. The cuts were done at different angular positions to characterize imposed peripheral inhomogeneities (0°, 90°, 180°, 270°). Due to the material removal, the residual stresses will be rearranged in the remaining part, which leads to the appearance of a deflection of the remaining material. This bending was used to try to estimate the residual stress levels previously present in the bars.

Key words: cold-drawing, residual stress, deflection methods.