Hot rolling refers to rolling performed above the metal recrystallization temperature.
Recrystallization means that when the annealing temperature is high enough and the time is long enough, strain-free new crystal grains (recrystallization core) are generated in the fibrous structure of the deformed metal or alloy, and the new crystal grains continue to grow until the original deformed structure is completely When the metal or alloy disappears, the properties of the metal or alloy also change significantly. This process is called recrystallization. The temperature at which new grains begin to form is called the starting recrystallization temperature, and the temperature at which the microstructure is completely occupied by new grains is called the end Recrystallization temperature, generally what we call the recrystallization temperature is the arithmetic average of the starting recrystallization temperature and the final recrystallization temperature. Generally, the recrystallization temperature is mainly affected by the alloy composition, deformation degree, original grain size, annealing temperature and other factors .
The above is the simple principle of theoretical hot rolling. The main manifestation in the actual production of our aluminum processing industry is that when the ingot is heated to a certain temperature in the heating furnace, that is, the rolling , And the determination of this temperature is mainly based on the phase diagram of the aluminum alloy, that is, in the most ideal case, the heating temperature is determined on the basis of the temperature at 80% of the solidus line of the alloy in the multivariate phase diagram. Involved in the problem of multiple phase diagrams of different alloys, the heating temperature is determined on the basis of 80% of the solidus of the alloy. In the implementation of the system, according to the actual production situation, according to the operation of the equipment, more modifications are obtained. Suitable for the production temperature of the alloy.
Features of hot rolling:
1. Low energy consumption, good plastic processing, low deformation resistance, insignificant work hardening, easy rolling, and reduced energy consumption required for metal deformation.
2. Hot rolling usually uses large ingots and large reduction rolling, with a fast production pace and large output, which creates conditions for large-scale production.
3. The as-cast structure is transformed into a processed structure through hot rolling, and the plasticity of the material is greatly improved through the transformation of the structure.
4. The characteristics of the rolling method determine that there is anisotropy in the properties of the rolled sheet. One is that the material has obvious performance differences in the longitudinal, transverse and height directions. The second is the deformation texture and recrystallization texture. There is obvious directionality in control performance.