Study of Bauschinger Effect by Reverse Shearing of 70:30 Brass

Abstract

Reverse shear experiments were conducted on a low stacking fault energy (SFE) material, namely 70:30 brass, and for comparison a high SFE material, namely commercial pure aluminum 1100, was chosen. Interesting results on the Bauschinger effect were observed. Appreciable Bauschinger effect was seen for 70:30 brass and this was explained through a new possible de-twinning theory, investigated here, which causes the fraction of twin to decrease during the reverse cycle leading to a decrease in the flow stress level. The other possible reason considered is the appreciable back stress developed due to the presence of obstacles (deformation twins) causing dislocation pile-ups, a theory previously investigated. The de-twining hypothesis was verified using deformation path change tests (changing deformation mode from simple shear to simple compression). It was also seen that the Bauschinger effect was negligible for aluminum (a high SFE material). Microscopic study was conducted on the sheared samples to study the microstructure evolution during forward and reverse shear deformation. Keywords: Bauschinger effect, Simple shear, Brass, Aluminum, Deformation twinning