Computational Design of Complex Microstructures for Advanced Engineering Alloys

点击翻译按钮获取中文摘要

High performance steels and advanced titanium alloys are essential materials for lightweighting in the transportation, energy and construction sectors. For example, 10% weight reduction in vehicles and aircrafts, respectively, decreases greenhouse gas emission by 6-8% and is also critical to enable alternative fuel vehicles. Thus, any improvement in processing and in-service performance of advanced steels and titanium alloys contributes significantly to engineering solutions with reduced environmental impact. In both materials, phase transformations occur in the solid state, i.e. transitions between different crystal structures as the temperature is increased or decreased during processing. Design of microstructures through these phase transformations is a key metallurgical tool to tailor the mechanical properties for specific applications. Phase field modelling is a powerful tool to describe and visualize the evolution of microstructures with complex morphologies as frequently found in steels and titanium alloys. In addition, phase field modelling is also an appropriate method to simulate the fracture behaviour in a wide range of materials. A physically consistent phase field approach has yet to be developed to predict for steels and titanium alloys representative multi-phase microstructures with complex morphologies and the resulting fracture behaviour. Depending on the processing path polygonal, plate-like and irregularly shaped transformations products may form thereby offering an enormous potential to optimize properties. The objectives of the proposed program are to develop a through-process phase field model for phase transformations in steels and titanium alloys with a multiplicity of transformation products and to predict the fracture behaviour of the resulting microstructures. Further, the role of potentially non-homogeneous distributions of alloying elements will be explored with phase field simulations to design microstructures using the concept of chemical patterning as a new avenue to improve material properties, e.g. fracture toughness. The program will offer training for two PhD students and five undergraduate summer students who will acquire a highly sought state-of-the-art skill set in computational engineering. The novelty and significance of the proposed research will be the advancement of the phase field method to a microstructure design tool for complex-phase steels and titanium alloys. A particularly exciting aspect of the proposed program is that microstructure simulations will be coupled with the prediction of the resulting fracture behavior in the phase field simulation framework, which will constitute an important novelty in the field. The proposed modelling method is expected to provide an attractive computational tool for next generation industrial process models by guiding microstructure design to optimize processing and properties of advanced metallic alloys as an important aspect of digital manufacturing.