SOME INVESTIGATIONS ON THE FORMING BEHAVIOR OF AN INDIGENOUS EXTRA-DEEP DRAWING LOW-CARBON STEEL .2. COMPARISON WITH THEORETICAL PREDICTION

Since the early eighties, cold rolled, close annealed, extra-deep drawing (EDD) grade steel is being indigenously produced (to specification SS 4011). Theoretical Forming Limit Diagrams (FLDs) of this steel were evaluated for six randomly selected heats using the classical plasticity approach. For the tension-compression region of the FLD, the modified equations of Hill for localised necking were used. For the tension-tension region of the FLD, the equations of Swift and Moore-Wallace for diffuse necking were employed. The theoretical FLDs were found to lie well below the experimental FLDs for all stress states. This emphasises the importance of evaluating the FLDs experimentally, if the material ductility is to be exploited fully in production. For a closer correspondence between the theoretical and experimental FLDs, the theoretical approach needs to be developed further.