Strain relaxation in a Linear Friction Welded Ti alloy

Linear Friction Welding (LFW) can achieve the high integrity joints required for lightweight fan blade and disk assemblies in future more efficient aeroengines. However, the process generates residual stresses that limit component life. Stress relaxation through post weld heat treatment (PWHT) is effective, but insufficient is currently known about how the varying microstructure affects the local relaxation rate for optimal PWHTs to be defined. This proposal seeks to perform in situ measurements of strain relaxation during PWHTs of Ti-6Al-4V LFW welds at temperatures representative of those being considered in industrial practice whilst accounting for the spatial variations in both microstructure, properties and residual stress across the weld.