Analytical and Experimental Evaluation of Flow Characteristics of Annealed AISI 304 Stainless Steel Sheet in Multi-Scale Bulge Forming

Micro and multiscale material properties are one area that must be considered in order to satisfy the need for increased utilization of miniature devices manufactured with microscale hydroforming processes. The objective of the present research is to evaluate the properties of 0.2-mm thick AISI 304 stainless steel using circular dies of 5 mm and 11 mm diameter and elliptical hydraulic bulge forming processes with minor diameters of 11 mm and various aspect ratios. Macroscale analytical methods for circular dies were compared to experimental results. For the elliptical dies, Banabic’s method and a new modification of Banabic’s method, utilizing work by Rees were used to obtain power law material properties. The Ekineev-Kruglov method was shown to be the best analytical method estimating material properties from circular dies. For elliptical dies, based upon finite element simulations, it was seen that Banabic’s method resulted in the best agreement with experimental results. However, it was found that neither method for elliptical dies resulted in reasonable dome height predictions compared to those from microscale tensile tests.