Ritwik Bandyopadhyay¹, Michael D. Sangid¹; ¹Purdue University

Linear friction welding, of similar or dissimilar Ti alloys, offers a promising technology for producing large, net shaped components with assured or tailored properties. The residual stresses of Ti64-Ti64 and Ti64-Ti5553 welds are quantified via energy dispersive x-ray diffraction for the as-welded and post-weld heat treatment conditions, and the associated microstructures are analyzed by backscatter electron imaging. For these materials, fatigue failure is prone to occur in the Ti64 base material, which experiences anomalous fatigue behavior at high R ratios. To investigate this phenomenon, strain accumulation and crack initiation are investigated in various samples with and without microtextured regions via high-resolution digital image correlation and complemented with crystal plasticity modeling. In this work, the anomalous mean stress behavior experienced by Ti64 at high R ratios is explained by high creep sensitivity, activation of the pyramidal slip systems, and degree of micro-plasticity resulting in increased fatigue damage at high R ratios.