Abstract
Abstract
The tribological mechanisms governing microstructure evolution in incremental sheet forming (ISF) were investigated through comparative analysis of three friction modes: sliding friction (ISF-SF), rolling friction (ISF-RF), and frictionless free deformation (ISF-FD). Systematic characterization of interfacial interactions, grain refinement mechanisms, and texture evolution demonstrated that friction-induced shear deformation served as the dominant factor in determining forming performance. Crucially, ISF-RF preserved {110} texture integrity via nondirectional shear deformation, where effective lubrication suppressed interfacial plowing, adhesion, and oxidation, thereby achieving superior surface finish and minimal twist angle in the formed parts. Conversely, ISF-SF drove directional shear deformation that actively reoriented grains toward the {001} texture. Reduced lubrication efficacy intensified the texture strength while amplifying interfacial plowing, adhesion, oxidation, and crack propagation, ultimately increasing the part twist angle. The study elucidated the mechanism by which friction governs forming performance through shear deformation: Moderate deformation coupled with grain refinement enhanced formability, whereas excessive deformation led to detrimental effects, including stress concentration, interface defects, and oxidation-accelerated failure. These findings establish a microstructure-property-process relationship, advancing ISF technology toward texture-regulated friction mode selection and adaptive lubrication strategies that balance grain refinement and defect suppression. This theoretical foundation enables next-generation ISF systems with enhanced forming limits and tailorable material properties.