Biaxial Stretching Behavior of a Copper-Alloyed Interstitial-Free Steel by Bulge Test

Biaxial stretching behavior of a promising high-strength copper-alloyed interstitial-free (IF) steel has been investigated under various processing conditions using bulge tests. Hill theory and von Mises yield criterion have been used to analyze the results. It is revealed that copper-alloyed IF steel in continuous-annealed (CA) condition exhibits the highest equivalent strain at fracture and largest limiting dome height (LDH) among all the processing conditions. However, these values are lower in copper-alloyed interstitial steel than in traditional interstitial-free-high-strength (IF-HS) steels due to the presence of solute copper and copper precipitates in the former.