The effect of prestrain temperatures on dislocation cell formation and subsequent tensile behavior in low carbon steel sheets

The effect of cellular dislocation substructures on the flow stress of AKDQ steel sheet was studied in interrupted-temperature tensile tests performed at temperatures between {minus}72C and room temperature. Subsequent work hardening from a given stress level was unaltered by the prestrain temperature, although the dislocation cell structure was dramatically altered. It was therefore concluded that the presence of a dislocation cell structure, as seen in TEM, does not dominate tensile work-hardening behavior in this material in a regime defined approximately by temperatures at and below room temperature, and strain rates at and above 1 {times} 10{sup {minus}4}s{sup {minus}1}. In this regime, the stress-strain behavior can be adequately described by a single-structure-parameter model, which implies the existence of a single structural feature, independent of the cell structure, which dominates the flow stress. The extent of development of this parameter is a function of the previous strain history, and the current deformation conditions. At higher temperatures (100C), the behavior is more complex, and a single structural parameter is no longer adequate.