The goal of the project is to develop a digital twin of state-of-the-art open and closed die hot forging processes used for manufacturing high-performance titanium alloy components. This will be achieved by developing novel experimentally-informed multi-scale materials simulations to build up forging behaviour maps as a function of the manufacturing variables. Property-determining microscopic changes will be evaluated using physics-based phase field models, which will feed local material property data into global finite-element models of component forging.
The structural integrity of titanium alloys is especially sensitive to variations in the microstructure. Components are typically closed die forged from sections of larger billets, and the billets are shaped from cast ingots using a series of open-die forging steps. Open die forging is needed to break up the coarse microstructure of the precursor ingots, which themselves are produced using a sequence of several melting and re-solidification steps to increase their purity and homogeneity.
Any non-uniformities and defects retained from the earlier stages are most often inherited throughout the subsequent steps in the long processing sequence. Furthermore, achieving a high degree of microstructural control becomes progressively more difficult as manufacturers try to forge larger components, due to existing stress and temperature gradients and residual stresses.
As much as 70% of material has to be machined away due to microstructural inconsistencies, requiring billets to be considerably larger than the final parts. Furthermore, to allow for possible microstructural inconsistencies, components may be manufactured to satisfy more conservative safety margins and simpler geometries, which increases their weight. This is a clear detriment to fuel efficiency for the aerospace manufacturers – which are major users of titanium forgings.
To solve these challenges, it is essential that the component-scale deformation models used by the digital twin reflect the microstructural sensitivity of real titanium alloys.
The following tasks will form the main objectives of the project:
- development of novel phase field models that can accurately replicate the property-controlling microstructural transformations in titanium alloys during hot forging
- development of a specialised modelling algorithm that will link the concurrent microscopic and component scale models. The algorithms will be responsible for the exchange of property and deformation condition data between the phase field and finite element models respectively, as well as the generation and administration of the necessary RVEs
- validation of the new models as a framework for the digital twin. This will involve the simulation of suitable open and/or closed die forging of real components over a range of processing conditions. This will be used to map out the microscopic and macroscopic properties of the final product as a function of the various process parameters. Such maps would then be suitable for informing manufacturers regarding the optimal hot-deformation conditions and troubleshooting the forging sequences, as well as effectively optimising the component geometries as new technological capabilities emerge
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