INSTABILITY OF SECONDARY RECRYSTALLIZATIO N CAUSED BY EXCESSIVE COLD-ROLLING REDUCTION IN FE-3-PERCENT SI ALLOY

In the presence of AIN and MnS precipitates in an Fe-3%Si alloy, secon dary recrystallization characterized by final heavy cold rolling was i nvestigated with special reference to the phenomenon of unstable secon dary recrystallization caused by excessive cold-rolling reduction. Exc essive cold-rolling reduction produces smaller grains, which are chara cterized by more {100}[025] oriented grains and higher possibility for the {100}[025] oriented grains associated with 15 coincidence boundar ies in the primary recrystallized specimen. An enhancement of the grai n growth of the {100}[025] primary recrystallized grain is considered to cause unstable secondary recrystallization by reducing the driving force of grain growth for the secondary recrystallized grain. It may b e essential for this unstable secondary recrystallization that the pre sence of two equivalent orientations of the {100}[025] oriented grain which is increased with higher cold-rolling reduction, have the SIGMA5 coincidence orientation relationship with each other.