Table of Contents
What is meant by dynamic recrystallization?
Dynamic recrystallization (DRX) is a type of recrystallization process, found within the fields of metallurgy and geology. In dynamic recrystallization, as opposed to static recrystallization, the nucleation and growth of new grains occurs during deformation rather than afterwards as part of a separate heat treatment.
How does Hot Rolling affect microstructure?
The microstructural changes that occurred in the hot rolled specimens were elongation of grains in rolling direction, nucleation of new grains at the grain boundaries of elongated grains and growth of nucleated grains to form fully recrystallized grains.
What is static recrystallization?
Following static recovery, there is partial or complete softening of the microstructure by static recrystallization, usually described as taking place in two stages: nucleation of new grains and the growth of these grains at the expense of deformed ones.
What factors affect recrystallization?
The main factors that affect recrystallization are:
- Temperature and time.
- Degree of cold work.
- Purity of the metal.
- Original grain size.
- Temperature of deformation.
What is dynamic recovery metal?
DRV is the only softening mechanism in commercial aluminum and its alloys when they are hot worked at strain rates of 10−2–102 s−1 at temperatures higher than 350 °C.
What is the purpose of hot rolling?
Hot rolling is a metalworking process in which metal is heated above the recrystallization temperature to plastically deform it in the working or rolling operation. This process is used to create shapes with the desired geometrical dimensions and material properties while maintaining the same volume of metal.
What is secondary recrystallization?
Secondary recrystallization is the phenomenon in which a certain very small number of Goss grains grow selectively (about one in 106 primary grains) at the expense of many other primary recrystallized grains. The development history of GO steel production has been reviewed by Xia et al.
Why is a hot solvent used in recrystallization?
In recrystallization, a solution is created by dissolving a solute in a solvent at or near its boiling point. At this high temperature, the solute has a greatly increased solubility in the solvent, so a much smaller quantity of hot solvent is needed than when the solvent is at room temperature.
What is the recrystallization temperature and how is it affected by longer annealing times?
It can be seen that with the increase of annealing time and annealing temperature, the volume fraction of recrystallization increases to more than 60%, and the large deformation grains almost disappear. After annealing at 430 °C for 8 h, the deformed grains are basically transformed into small recrystallized grains.
What is the difference between recovery and recrystallization?
While recovery describes the gradual re-ordering and annihilation of the stored dislocations, primary recrystallization proceeds discontinuously by the formation and motion of high angle grain boundaries which discontinuously sweep the deformation substructure.
What is material dynamic recovery?
To include dynamic recovery, one can consider the annihilation of stored dislocations—a process that involves their leaving the glide planes on which they are stored at impenetrable obstacles. From: Unified Constitutive Laws of Plastic Deformation, 1996.
What are the three main types of recrystallization?
Recrystallization involves several different types of approaches for the purification process based on the condition of the solution and on the solid required to be recrystallized.
- Single solvent recrystallization.
- Multi solvent recrystallization.
What is recrystallization in hot working?
If we heat the metal to elevated temperatures and deform it in that temperature, the strain hardening phenomenon does not occur. New grains are occur that free of strains at elevated temperature deformations. So this phenomenon is called as recrystallization.
What is the principle of hot rolling?
What is hot rolled process?
Hot-rolling refers to a mill process in which you roll the steel at a temperature above its recrystallization temperature; a heat that typically exceeds 1000° F. When steel is heated past its recrystallization point, it becomes more malleable and can be properly formed and shaped.
What is dynamic recrystallization?
Dynamic recrystallization (DRX), which is a critical regulatory procedure in the hot rolling process, can greatly improve the microstructure of metallic materials.
How to avoid dynamic recrystallization during hot rolling?
These factors are especially important in hot rolling that aims at uniform refined hot rolled microstructure. This can be achieved by avoiding dynamic recrystallization (DRX) of austenite during hot rolling passes and static recrystallization between them and before cooling.
How to recognize dynamic recrystallization in a stress–strain curve?
In a stress–strain curve, the onset of dynamic recrystallization can be recognized by a distinct peak in the flow stress in hot working data, due to the softening effect of recrystallization. However, not all materials display well-defined peaks when tested under hot working conditions.
What is XMD in metadynamic recrystallization?
In Eq. (5.86), XMD is the volume fraction after metadynamic recrystallization, calculated from the Avrami equation with k =1.5. The dynamic recrystallization-controlled steels are those that are given very little time between rolling processes to achieve austenite grain size of ≤ 10 μm.