The strain-hardening response was studied during tensile deformation at temperatures of between 200 and 1200C. At temperatures of up to 600C, two hardening stages were observed which were associated with dislocation/dislocation and dislocation/solute interactions. An increase in the temperatures, to 700C, resulted in the introduction of a third hardening stage. Transmission electron microscopy suggested that this additional hardening stage arose because of a transition, in the dislocation arrangement, from random tangles to cellular sub-structure. At temperatures of between 750 and 1200C, a single hardening stage was observed. Transmission electron microscopy showed that this was associated with a cellular/sub-grain dislocation sub-structure. An analysis of the results indicated that the third stage of hardening, at temperatures of between 600 and 700C, and the single-stage hardening, between 750 and 1200C, could be described by the Bodner-Partom and/or Kocks-Meeking dislocation/dislocation interaction models. At temperatures of between 750 and 950C, the hardening behavior could be described by the modified Kocks-Meeking dislocation and constant periodic barrier size interaction model.

Elevated Temperature Hardening of Inconel 690 V.Venkatesh, H.J.Rack: Mechanics of Materials, 1998, 30[1], 69-81