A Review on Formability of Tailored Sheets in Incremental Forming

Abstract

This chapter presents a review on formability study of tailored sheets produced through welding and laminations of dissimilar metallic and non-metallic sheet materials with varying layering conditions in incremental forming. Forming limit curve (FLC) and maximum forming wall angle of different tailored sheets namely tailor welded blank (TWB), tailored bimetallic sheets (TBS), and tailored laminated blank (TLB) were predicted through incremental sheet forming (ISF) tests. Formability of the TWBs made by friction stir welding (FSW) with optimal weld quality determined through parametric study was investigated through prediction of FLCs by ISF line test considering different forming conditions. Formability of friction stir TWBs was found to be lower compared to that of the base sheets in incremental forming. Incrementally formed samples of the TWBs had higher hardness due to lower strain hardening effect, and exhibited a mixed ductile and brittle mode of failure. Formability and failure of TBS in incremental forming depends on layer arrangement and material type. Forming force, surface quality, thickness variations, fracture, and delamination etc. in incremental forming of TBS can be controlled by suitable selection of process parameters and layer arrangement. Formability of TLBs made of metallic and polymer sheets was seen to be higher than both the individual sheets for plane strain case. However, failures like bump structure, delamination, and tearing were seen to occur in incrementally formed TLBs. It was shown that these defects could be reduced by employing discontinuous toolpath instead of the conventional continuous toolpath.