Abstract
Observations were made on the plastic deformation of iron single crystals subjected to the simple shear on the single and multiple slip systems to examine the work hardening behavior. When the applied shear stress was matched to the single slip systems, the easy glide in stage I was clearly observed in the stressstrain curves. On the other hand, when the applied shear stress coincided with the multiple glide system, the linear hardening in stage II was clearly recongnized from the early stage of deformation.
To examine the work hardening mechanisms, the strain rate-cycling tests were performed on crystals in easy glide and linear hardening regions and the average effective and internal stresses were estimated as a function of strain in these regions.
In the easy glide in stage I. the effective stress is essentially independent of the strain whilst the internal stress increases with strain. The work hardening in stage I resulted from the increased long range internal stress field due to dislocation tangles and cell walls. On the other hand, the work hardening in stage II is caused by the increase in both internal and effective stresses. The ratio of the internal and effective stresses is approximately 2.6. This result suggests that the work hardening in stage II is associated with the long range internal stress field as well as the hardening in stage I.
