Experimental Investigations on Stretchability of an Austentic Stainless Steel 316L

The purpose of this investigation is to examine the viability of using the sheet metal for forming applications. Forming limit diagram (FLD) composed of negative and positive minor strain with respect to major strain which occurs at directional zero strain with the critical thickness of sheet metal. The negative minor strain region of FLD is predicted by localized necking. However there is no directional zero strain in the positive minor region of FLD is predicted with help of Marcinaik-Kuczynski assumption. The present work aims to determine the stretchability in terms of limiting strain of Austentic stainless steel 316L using M K analysis and hemi spherical dome stretching. Strain hardening exponent was derived from uni axial tensile test of Austentic stainless steel 316L under different in homogeneity conditions. C programme was developed to predict the theoretical FLD and results were compared with experimental value. The limiting strain of material is found as 0.4 in experimental and Marcinaik - Kuczynski analysis. Fractography shows the large amount of cleavage fracture and evidence for cleavage initiating because of other inclusions.