Simultaneous hardening and softening in a nonisoaxial β brass bicrystal

Nonisoaxial beta brass bicrystals, consisting of a hard (H) orientation, close to , and a soft (S) orientation near the center of the stereographic triangle, were compressed in both continuous and interrupted tests, which permitted slip line observations to be made, in order to ascertain why in previous work5 a similarH-S combination had shown much greater hardening in theH component. Stress-strain behavior of each component was determined by methods developed earlier.5 TheH component initially hardened rapidly with strain, and at 0.5 pct strain, hardened more slowly. TheS component revealed lower strength and strain hardening than the unbonded single crystal up to 1.5 pct plastic strain, after which hardening was much more rapid. From slip line observations considerations of the effect of secondary stresses, and examination of slip systems providing least work at the grain boundary, it appears that the reduced flow strength of theS component is due to pile-up stresses from theH component. Changes in strain hardening rate in bothH andS components were related to the onset or cessation of heavy slip associated with serrated yielding.