Recrystallization temperature of ABS plate deformation products

Recrystallization temperature of ABS plate deformation products

The recrystallization temperature of pure aluminum is very low. All alloy components in aluminum alloys can increase the recrystallization temperature; however, several major alloy components (copper, magnesium, zinc, silicon) can only slightly increase the recrystallization temperature. Using a small amount of transition metals (manganese, chromium, iron, aluminum, chromium, vanadium) as additives can significantly increase the recrystallization temperature of aluminum alloys. These transition metals are added to most aluminum alloys or are present in the alloy as unavoidable impurities. In alloys containing additives, the recrystallization temperature can be significantly increased either after hot deformation or after cold deformation. Although manganese, chromium and chromium can only slightly increase the recrystallization temperature of aluminum and aluminum alloys after cold deformation, their effect after hot deformation is much greater.

When the aluminum alloy composition does not contain transition metals, even under the most favorable conditions (stress state diagram, deformation temperature, etc.), its recrystallization temperature is much lower than the tempering heating temperature (460-5300C). Only by using transition metals (mainly manganese, chromium and alumina) as additives can the recrystallization temperature of many semi-finished products be higher than its quenching heating temperature. Therefore, adding transition metals to the alloy is one of the conditions for structural strengthening.

The mechanism of the influence of transition metals on recrystallization temperature is as follows. When the ingot crystallizes, the transition metals present in the alloy form a stable solid solution with aluminum. Since the equilibrium solubility of transition metals in aluminum is very small in the solid state, the solid solution is supersaturated not only at room temperature, but also at heat treatment temperatures and heat deformation temperatures. Therefore, during the heat treatment of ingots and during process heating and pressure processing, these solid solutions will decompose and precipitate dispersed particles of intermetallic compounds of transition metals and aluminum.

In aluminum alloy deformed products containing transition metals, there are often inclusions of intermetallic compound particles of manganese, chromium and other metals. They are products of the decomposition of the supersaturated solid solution formed by transition metals in aluminum during crystallization, and the degree of dispersion of these particles depends on the production process of the semi-finished product. Since the particles of the intermetallic compound can fix the dislocations, they prevent the redistribution of the dislocations during heating, and the redistribution of the dislocations is precisely the necessary condition for the formation of the recrystallization center. Therefore, the recrystallization temperature is increased. The more particles and more dispersed the intermetallic compounds of transition metals in the alloy are, the higher the recrystallization temperature will be. It has been established that when transition metals are present in solid solution or in the form of coarse condensed particles, they can only slightly increase the recrystallization temperature of the alloy.