Residual Stress Evaluation of a High Performance Machined Pre-formed Ti6Al4V Part

Near net-shape technologies are increasingly used to enhance resource efficiency in high performance machining for various applications, including aerospace. In this paper the effect of a pre-formed based manufacturing route on the residual stress state of an aerospace part in Ti6Al4 V is presented. The manufacturing strategies, including the pre-form and machining stages, are outlined in detail. Two similar preformed billets were manufactured. High performance machining was then conducted at two different laboratories to manufacture a similar part utilizing different machining strategies. The effect of the manufacturing route and strategies utilized on the residual stress state of selected regions of the part were then evaluated by XRD (surface) and neutron diffraction (body) techniques. The results show that productivity improvements can be realized by utilizing a pre-form without incurring noteworthy residual stresses as a result of the forming process. The surface residual stress state, however, is substantial and found to be largely a function of the cutting strategy applied.