Strain hardening aluminum alloys

aluminum cold deformation

Нагартовка (наклеп) It occurs during the cold deformation of the product. During plastic deformation alyuminevogo alloy at a temperature below that, при которой происходит возврат и/или рекристаллизация (для алюминия – usually lower 150 °C), дислокации в структуре металла имеют возможность передвигаться (обеспечивать пластическую деформацию) и размножаться. The movement and multiplication of dislocations leads to an increase in their density, and entanglement among themselves. Therefore each subsequent plastic deformation takes more energy. The metal becomes harder, with a high yield. The greater the degree of deformation or strain hardening, the more pronounced this effect.

Нагартовка алюминия и алюминиевых сплавов возникает в ходе любой холодной деформационной обработки изделий: холодной прокатки, deep-drawn, shoeing, flanging and even ordinary coiling.

aluminum annealing

Операция отжига имеет две фазы: 1) «возврат» или «отдых» и 2) «рекристаллизация». During the return, there is some "softening" of the metal as a result of restructuring and dislocation annihilation, bringing the released internal energy stored plastic strain. Return begins at a temperature generally 0,3 от температуры плавления (в градусах Кельвина). In the recrystallization step in some areas material undeformed grains nucleate, that grow and absorb all the distorted, or "rested" as a result of the microstructure of return. Further heat treatment results in grain growth and coarsening. The result is grain coarsening, that grain boundaries becomes smaller. The grain boundaries act as barriers to movement of dislocations. therefore, fewer barriers, the less energy is required to dislocations movement, a, Consequently, metal is easier to deform plastically. It becomes softer and more pliable.