Forming limit diagram and void coalescence analysis of AA5052 coated with molybdenum-based ceramic nanocomposites

Aluminium 5052 alloy sheets of size 75 × 25 mm and 3 mm thickness with double edge semicircular notches of diameter from 2-8 mm have been coated with MoSi2-SiC nanocomposite coatings by sputtering process. The structural morphology of the ceramic coatings was explored by Fourier Transform Infrared (FT-IR) spectroscopy, X-ray Diffraction (XRD) analysis, Scanning Electron Microscopy (SEM), and Atomic Force Microscopy (AFM). The coated and uncoated sheet samples were subjected to tension-compression state of strain up to fracture by varying the notch sizes using INSTRON Universal Testing Machine (UTM). Fracture behaviour studies of the sheets were performed and forming limit diagram (FLD) was drawn. The void coalescence analysis was also carried out by using SEM images and the effect of coating behaviour of combined forming and fracture were analyzed. In the coated sheet, the L/W ratio was very close to 1.0. Thus, no oblate/prolate voids were observed and the heat generated during deformation was retained for longer time and thereby adiabatic shear band formation has occurred with increased formability.