A criterion for shear banding localization in polycrystalline FCC metals and alloys and critical working conditions for different microstructural variables

Abstract

This article investigates the effect of stress state on the shear banding localization and microstructure evolution in polycrystalline FCC metals and alloys. It is worth to indicate that this investigation was previously conducted on 70/30 brass and extended through the present work to include different stacking fault energy (SFE) materials ranging from low SFE alloys; such as 316L Stainless steel to medium SFE metals such as copper to examine the generality (if any) of the previous findings in 70/30 brass. Stress states investigated are plane strain compression (PSC) and simple compression (SC). It is known that shear bandings are more likely to develop vigorously in PSC. The tests were also conducted on specimens with different grain sizes. It was shown that the strain hardening rate curves of SC and PSC coincided up to a certain value of an effective strain beyond which the hardening rate curve of PSC started to deviate and drop rapidly, which indicated the presence of extensive shear banding. These observations were verified through detailed optical microscopy of deformed specimens at these strain values.