Finite Element Modelling and Experimental Testing of Thermomechanical Behaviour and Failure of Titanium Superplastic Forming Dies

Abstract

This paper describes high temperature cyclic and creep relaxation testing and modelling of a high nickel-chromium material (XN40F) for application to life prediction of superplastic forming (SPF) tools. An experimental test programme to (i) characterise the high temperature cyclic elastic-plastic-creep behaviour of the material over a range of temperatures between 20oC and 900oC, including cyclic controlled strain-range tests at different strain-rates and creep relaxation tests, and (ii) identify the material constants relevant to thermo-mechanical fatigue (TMF) life prediction, is described. The objective of the material testing is the development of high temperature material and failure models for cyclic analyses and life prediction of SPF and diffusion bonding (DB) dies for titanium aerospace components.