Abstract

A range of problems relevant to metal forming will be discussed, where grain characteristics (size, regularity, relative orientation), or second phase interfaces play an important role in the deformation, in some cases leading to size effects. Applications will include micro-pin extrusion, micro-tube hydroforming, warm sheet forming (e.g. stamping, superplastic forming) and hot rolling. A selection of modelling methods capable of capturing some of the effects of microstructure in metal forming will be used in corresponding simulations, including a crystal plasticity extended finite element method, crystal plasticity equations calibrated by discrete dislocation simulations and a concurrent coupling of discrete dislocation plasticity and a crystal plasticity finite element method. Algorithms recently developed for the generation of microstructures will also be presented, based on a controlled Poisson Voronoi tessellation determined by a unique mapping between parameters obtained from physical microstructures and the virtual grain distribution, with interfaces modelled by cohesive zones; adaptation of the algorithms for creating continuously graded microstructures, such as locally recrystallised or case hardened material, will be demonstrated. The grain structure generation software will be used as a pre-processor in many of the metal forming simulations. Limitations of the cohesive zone approach for interfaces will also be highlighted as motivation for the further development of extended finite element methods for microstructure modelling.