Strain Path Effects in Metal Plastic Forming: Mechanisms, Characterization, and Application

Strain path is a critical factor governing the forming quality of metallic components, including their geometry, microstructure, and service performance. Achieve high-quality forming often requires the use of nonlinear and complex strain paths, which inevitably give rise to multiscale deformation behaviors. Understanding and characterizing these mechanisms has therefore become a frontier topic in the field of plastic forming. This review synthesizes recent advances in the investigation of macroscopic mechanical responses, damage behavior, and microstructural and textural evolutions under complex strain paths, emphasizing the central role of stress path history in shaping multiscale deformation mechanisms. Finite element modeling strategies that account for strain path effects are discussed, including constitutive models, limit prediction and damage models, as well as microstructure evolution models, with particular attention to their roles in improving predictive accuracy and process simulation capabilities. Engineering-oriented approaches to strain path design are also summarized, highlighting their potential for optimizing formability and service performance. Finally, perspectives on future research directions are presented.