Dynamic Recrystallization During High Temperature Low Cycle Fatigue of Nickel: Progress Report for Period June 1, 1986-May 31, 1987

摘要

Dynamic recrystallization during high temperature LCF of Ni and its effect on mechanical properties was investigated. Dynamic recrystallization was found in polycrystals, even at total strain amplitudes as low as 0.004. Dynamic recrystallization was nucleated at grain boundaries. No dynamic recrystallization could be initiated in a single crystal with 1% strain amplitude up to 300 cycles. Concurrent grain boundary migration and sliding was observed. These processes lead to considerable grain growth, while dynamic recrystallization tends to refine the grain size. The cyclic hardening curve invariably reveals a maximum, which cannot be attributed solely to dynamic recrystallization, because of the softening due to grain boundary realignment and grain coarsening. B-doped Ni sub 3 Al gave results similar to Ni. The kinetics and microstructural development of deformed Ni sub 3 Al was studied. The development of the deformation structure is similar to Ni but the texture development is quite different. Recrystallization was observed to start early at deformation inhomogeneities, but the recrystallization kinetics are fairly slow. A feasibility study regarding the use of synchrotron radiation for the determination of grain boundary distributions was successful. (ERA citation 12:018525)