Effect of Formability Process Parameters in Dynamic Strain Ageing Region of Austenitic Stainless Steel

The consumption of Austenitic Stainless-Steel ASS 304 has been increasing recently in the outer body of Automobile applications. Sheet Metal Forming is one of the processes used to convert ASS 304 sheet into an end product. ASS 304 has good ductility with the rise in temperature up to 450^oC and later dynamic strain aging (DSA) in the temperature range 450- 600^oC. Formability studies of ASS 304 in the DSA region and the effect of process parameters like anisotropy and strain rate are investigated in the present paper. Stretch forming Investigations have been carried out at a temperature of 500^oC in two quasi-static strain rate ranges 1x 10^-4 s^-1 and 1x 10^-1 s^-1 concerning three orientations parallel (R₀), diagonal (R₄₅) and Transverse(R₉₀) to Rolling Direction. The experiments were carried out at both the necking and fracture regions. Deformed specimens' major and minor strains are measured to plot Fracture Forming limit Diagrams, strain distribution, and limiting Dome height. Particular attention is given to the evaluation of strain rate and orientation of the sheet concerning rolling direction on formability.