STUDY ON DEEP DRAWING BEHAVIOR OF THE INTERSTITIAL FREE STEEL IN CORRELATION WITH THE MICROSTRUCTURE

Abstract

The objective of this paper was to present results obtained about the behaviour of the IF steel associated with high deformation. To evaluate the deep drawing aptitude, samples were subjected to tensile test, n and r values determination, hole expansion and Erichsen tests. The results were correlated with a microstructural study. Through thermodynamic simulation, the phase transformation temperature (Tg®a) and the precipitates formation were estimated. The Tg®a value was also determined by dilatometry test. The failure of the material during deep drawing or stamping process is evidenced through the formation of cracks in areas with critical angles changes. It was relevant to understand the mechanisms of fracture nucleation and propagation of the IF steel. A fractography study was carried out and was possible to verify the presence of cavitation mechanism as results of the superplastic flow at high deformation conditions, promoting necking and fracture after a high plastic deformation achieved.