Experimental Investigation on Stretchability of an Austentic Stainless Steel 316L

Forming limit diagram (FLD) is 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 which could be predicted with the 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. C++ program was developed to predict the theoretical FLD and the results were compared with the experimental value. The limiting strain of material is found as 0.4 in the experimental and Marcinaik - Kuczynski analysis. Fractography shows the large amount of cleavage fracture and becomes an evidence for cleavage initiating due to other inclusions.

Keywords:

Forming Limit Diagram (FLD) , Marcinaik-Kuczynski analysis , Simulation in C++ , Sheet Metal