Effect of Titanium Alloy Class on the Fatigue Response to Mechanical Surface Treatments

摘要

The goal of this overview was to outline potential improvements in fatigue performance of the various titanium alloy classes by mechanical surface treatments such as shot peening and deep rolling. Alloys covered belong to α, near-α, (α+β), and metastable β alloy classes. In addition, results on a titanium aluminide γ(TiAl) are also presented. After shot peening, marked differences were found in the process-induced micro-hardness-depth profiles among the various alloys which correlated with the work-hardening capability seen in the tensile tests. Most pronounced improvements in HCF life after shot peening were observed on the α-titanium alloy Ti-2.5Cu and the titanium aluminide γ(TiAl) while only slight improvements were found on the metastable β alloys such as Beta C. Near-α and (α+β) alloys showed an intermediate response. The fatigue results are interpreted with the cyclic stability of the process-induced changes in microstructure and residual compressive stresses which were found to correlate with the cyclic deformation behavior (hardening/softening) of the various alloys.