A macro-micro constitutive model of Aermet100 ultra-high strength steel under multi-field coupling of force-electricity-heat

Electropulsing assisted forming technology demonstrates significant application potential by reducing deformation resistance and enhancing the forming limits of difficult-to-deform materials. However, constitutive models incorporating key electropulsing parameters have not yet been established, leading to substantial errors in electropulsing assisted forming experiments conducted across different current application equipment. In this work, Aermet100 ultra-high strength steel as the research object, based on the influence of electropulsing process parameters on dislocation multiplication and annihilation, a high-temperature electroplastic constitutive model under thermo-electro-mechanical multi-field coupling was developed. Conventional hot compression experiments and electropulsing assisted high temperature compression experiments were performed on Aermet100 steel. True stress-strain curves under the dual variables of forming temperature and strain rate were obtained, and material constants, including the deformation activation energy, were determined. The genetic algorithm was employed to solve the model parameters. The developed model accurately describes the flow stress of Aermet100 steel under various electropulsing parameters, achieving a correlation coefficient of 0.9539 between predicted and measured values. The electropulsing assisted local upsetting severe plastic deformation process served to validate the model. Accounting for errors introduced by specimen heating and the specimen removal approach, the simulation results can well reflect the actual microstructural morphology of the component. This study provides a theoretical and technical foundation for microstructure and property control during the high-temperature plastic deformation of difficult-to-deform materials assisted by pulsed electric current.