THEORY OF LOW TEMPERATURE WORK-HARDENING OF BODY-CENTRED CUBIC METALS

Stress-strain curves of bcc metals at low temperatures, where screw-dislocations predominate, are calculated for crystals with the [100] deformation axis. The main assumptions are (1) an increase of flow stress is proportional to the square root of forest dislocation density, (2) dislocations are multiplied by the cuttings of screw dislocations with repulsive elastic interaction, and (3) a screw dislocation annihilates with another dislocation with the opposite sign. The calculated stress-strain curve is compared with the observed stress-strain curves. It is concluded that the important property of screw dislocations in bcc metals is the easiness of cross-slip; this the origin of the variety of the work-hardening in bcc metals at low temperatures. © 1969, THE PHYSICAL SOCIETY OF JAPAN. All rights reserved.