Hybrid manufacturing of components from Ti-6Al-4V by metal forming and wire-arc additive manufacturing

Abstract

Abstract The manufacturing of components from the titanium alloy Ti-6Al-4 V is of great significance for many industrial sectors. The production of high-performance Ti-6Al-4 V components typically requires multiple hot forging steps and leads to parts with tolerances that need extensive machining to create the final shape. For many applications, net-shape technologies such as additive manufacturing (AM) could enable a higher material yield. However, with the part size, cost and processing time in AM rise rapidly. Thus, the advantages of AM and forging operations could be exploited by combining both processes to new hybrid process chains. The present study investigates the use of Wire-Arc additive manufacturing (WAAM) for hybrid manufacturing of Ti-6Al-4 V aerospace components. Two process routes are investigated that combine forming and AM processes. In the first process route, a WAAM process is used to generate a pre-shaped semi-finished part. The semi-finished part will then be forged using a single forming tool to obtain the final part contour. The second process route utilizes a conventionally forged pre-form, onto which features of the final workpiece are added using WAAM. The results confirm that hybrid technologies combining WAAM and forging are very promising for Ti-6Al-4 V part production. A jet engine blade produced by WAAM and subsequent forging shows microstructures typically produced in conventional processing of Ti-6Al-4 V alloy and exhibits tensile properties, which exceed the specification level of cast and forged Ti-6Al-4 V material. Features created by WAAM on forged pre-forms are shown to reach the mechanical properties required to combine both technologies. The combination of WAAM and forging may hence be used to develop new manufacturing chains that allow for higher material yield and flexibility than conventional forging.