Role of the dynamic and static softening mechanisms in multistage hot working

Abstract

After hot deformation, during either holding until the next pass or final cooling, static recovery takes place followed by static recrystallization in certain cases. The rate of classical static recrystallization depends on the accumulated strain energy and the temperature. The rate of post dynamic recrystallization depends on the above factors and on the occurrence of dynamic recrystallization during prior straining. The hot ductility is enhanced by increasing the ease of both dynamic recovery, which retards nucleation of intergranular cracks, and dynamic recrystallization, which hinders fissure growth by moving grain boundaries away from them. The presence of solutes and precipitates reduces workability by hindering dynamic softening but the static softening associated with multistage processing improves it. The strength and ductility of the hot worked product can be improved by refinement of the grains and by the retention of the deformation substructure if desired.