Forming limit diagram for interstitial free steels supplied by Ford India Motors

Forming limit diagrams are used by the stampers to solve sheet metal forming problems. In practice, sheet metals have been subjected to various combinations of strains. Necking during sheet metal forming sets the limit to which the sheet metal can be formed. Forming limit diagram is an effective tool to evaluate the formability of sheet metals in various strain conditions. The information upon the formability of sheet metals is important for both sheet metal manufactures and user. In this work, the formability of two sheets namely, interstitial free steel sheet of thickness 0.85 mm coated and noncoated, have been studied and their suitability for forming applications have been examined. The microstructural aspects, tensile properties and formability parameters of the above mentioned sheets were studied and the forming limit diagrams were evaluated for the above sheet metals. Strain distribution profiles obtained from the forming experiment have been analysed. The fracture surfaces of the formed samples were viewed using scanning electron microscope (SEM) and the SEM images were correlated with fracture behaviour and formability of the sheet metals. Both the sheets have been found to possess good drawability and stretchability.