The Influence of Induced Strain in Texture Heterogeneities on a Near-α Titanium Alloy for Aerospace Applications

Near-α titanium alloys are widely used in the aerospace industry for jet engine components. Despite the extensive control during processing, microstructure and texture heterogeneities are unavoidable during the early forging stages and they persist with further processing leading to heterogeneous properties in the final component. Alloys such as Ti834 are susceptible to the development of macrozones or regions with similar crystallographic orientation leading to a reduction in cold dwell fatigue life. The thermomechanical processing for compressor disc manufacture includes primary and secondary forging stages. However, the complexity of the strain path during secondary forging complicates the study of a single induced strain on the original macrozones. Pancake samples obtained by an intermediate upset forging stage are investigated here to evaluate the influence of a single compressive strain on the Ti834 billet texture. The macrozones are characterized as a function of strain and compared with equivalent levels of strain from billet and final component. Results revealed the presence of a strain threshold at which macrozone incoming from billet are drastically reduced in size.