Failure prediction for Titanium alloys using a superplastic forming limit diagram approach

Superplastic forming limit diagrams (SPFLDs) are presented for both Ti‐6Al‐4V and Ti‐6Al‐2Sn‐4Zr‐2Mo alloys. FE‐predicted ϵ1‐ϵ3‐ϵeq paths for key points on the forming blank are then plotted on the SPFLD to predict failure. A key factor for reliable SPF forming limit prediction is the incorporation of a mechanisms‐based constitutive model, which includes microstructural effects, such as static and dynamic grain growth and associated hardening, and with material constants independent of the forming strain‐rate. The sinh model of Dunne and co‐workers is thus employed. Results from forming trials for both materials are used to assess the failure predictions.