Does recrystallization result in grain refinement?
4.3. Recrystallization mechanisms in Mg based alloys. Grain refinement and improvement in mechanical properties during TMP of Mg alloys are often attributed to dynamic recrystallization because of their low stacking fault energy.
What are the factors governing final recrystallized grain size?
The recrystallized grain size as given by eqn [116] depends on the ratio of the materials surface energy to the elastic modulus, the network dislocation density, and the change in configurational entropy.
What do you mean by recrystallization?
Recrystallization is a process by which deformed grains are replaced by a new set of nondeformed grains that nucleate and grow until the original grains have been entirely consumed. From: Microstructure Evolution in Metal Forming Processes, 2012.
Does recrystallization increase grain size?
As a result, the recrystallization temperature will decrease with increasing deformation. Increasing the deformation, or reducing the deformation temperature, increases the rate of nucleation faster than it increases the rate of growth. As a result, the final grain size is reduced by increased deformation.
Why does recrystallized grain size increase with increasing temperature?
Grain boundaries are good sites for nuclei to form. Since an increase in grain size results in fewer boundaries this results in a decrease in the nucleation rate and hence an increase in the recrystallization temperature.
What do you mean recrystallisation temperature?
Hot rolling is carried out at temperatures above the recrystallization temperature of the metal. The recrystallization temperature is that temperature at which the crystal lattice structure of the metal becomes reoriented. Consequently, the metal becomes more workable and ductile.
Does grain size affect strength?
Smaller grains have greater ratios of surface area to volume, which means a greater ratio of grain boundary to dislocations. The more grain boundaries that exist, the higher the strength becomes.
Does recrystallization decrease grain size?
How is recrystallization related to the process of grain growth?
Thus the process can be differentiated from recovery (where high angle grain boundaries do not migrate) and grain growth (where the driving force is only due to the reduction in boundary area). Recrystallization may occur during or after deformation (during cooling or subsequent heat treatment, for example).
What happens to the coarse grain zone after extrusion?
The depth of the coarse grain zone is gradually reduced from the trailing end toward the front end to completely disappear. The formation mechanism is a sub-grain region formed on the surface layer of the product after hot extrusion, and forms a coarse recrystallized grain region after heat solution treatment.
How is recrystallization of a grain affected by Zener pinning?
Recrystallization is prevented or significantly slowed by a dispersion of small, closely spaced particles due to Zener pinning on both low- and high-angle grain boundaries. This pressure directly opposes the driving force arising from the dislocation density and will influence both the nucleation and growth kinetics.
How big is the coarse grain zone in aluminum?
The coarse grain zone is an annular coarse grain region formed on the periphery of the extruded product and is a structural defect of the extruded product. The grain size in the coarse grain zone may exceed 10 to 100 times the original grain size and up to 800 to 1500 btm.
