Microstructure and texture based analysis of forming behavior and deformation mechanism of AA1050 sheet during Single Point Incremental Forming

Abstract

In case of Single Point Incremental Forming (SPIF) process, the deformation mechanism, absence of material localization prior to fracture and enhanced formability are still not satisfactorily explained. The objective of this work is to understand the sheet deformation characteristics, forming behavior, and dominant deformation mechanism of SPIF process. Process deformation characteristics such as dimensional accuracy, thickness distribution, true surface strain, von Mises stress and equivalent plastic strain, evolved at different forming stages, were evaluated through experimental investigation and Finite Element Analysis (FEA) of the formed parts. The evolved microstructural features for different stages and modes of strains have been analyzed by Electron Back Scatter Diffraction (EBSD) and X-Ray Diffraction (XRD) techniques. Analysis has also been carried out to identify the reason of typical failure under biaxial strain mode. An abundance of {001} <100> Cube texture component in the early forming stage indicates the occurrence of dominant shearing in this stage. The intermediate forming stage develops dominant {011} <111 > P texture component, which remains intact up to the final forming stage. This shows that Particle Stimulated Nucleation (PSN) has taken place due to excessive strains occurring in the sheet material during SPIF, causing grain refinement and shear band formation, and simulating kind of recovery or recrystallization process. Enhanced formability in SPIF can be attributed to the depletion of {001} <100> Cube texture, and development of {011} <111 > P texture and {011} <211> Brass texture component with the progression of SPIF.