Comparison of Formability and Microstructural Evolution of C106 Copper and 316L Stainless Steel

Strain-hardenable materials achieve their strength due to the build-up of defects and dislocation tangles within the microstructure brought about by strain induced through processing or forming. This strength can be significantly reduced and negatively impacted if the material is used in service at elevated temperatures, which causes the grain structure to recover and recrystallize to a more organized, lower strength state. Forming limit curves of C106 DHP copper and 316L stainless steel were established using an Interlaken hydraulic press with Nakajima punch tooling and GOM digital image correlation cameras. These formed samples were used as an analog to current formed parts, and the effect of extant elevated operating temperatures was then investigated by means of microhardness testing. High-resolution electron backscatter diffraction (EBSD) analysis using a JEOL JSM-7800F field-emission gun scanning electron microscope was employed to understand the various mechanisms responsible for the physical and microstructural changes during forming and at elevated temperatures.