1、 What is secondary recrystallization? The aluminum plate manufacturer will introduce it to you:
Secondary recrystallization is the phenomenon that most of the grains in the recrystallized matrix of 5052 aluminum plate have a small growth trend (relatively stable), and only a few grains can grow rapidly. So what is the bar for secondary recrystallization? It is the stability of the matrix, which hinders the normal growth of grains. In that case, because of a certain perimeter, right? If they don't hinder the growth of grains, they will become the core of secondary recrystallization.
2、 Several factors affecting secondary recrystallization
Dispersion has the most obvious blocking effect on the normal growth of grains. Species retardation and its dispersion, volume fraction, distribution, aggregation and dissolution forces. If the barrier is small, the grains will grow normally. If the obstruction is large (for example, if the volume fraction of the dispersed phase is large, the recrystallized grains will be early stable, which will not only hinder the normal growth, but also make it difficult for some grains to obtain the chance of accidental growth. Only at the dispersion point, the resistance to grain growth is very strong, and because of some reasons (the most important is the rise of temperature), they gather or dissolve locally, thus reducing the resistance to the growth of some grains. In this case, these grains may become secondary recrystallization nuclei. Therefore, the secondary recrystallization caused by dispersed particles can only start to aggregate and coarsen gradually at annealing temperature. When it dissolves, it can happen. The secondary recrystallization of aluminum alloy is first related to alloy elements. When the elements such as manganese and chromium are formed, the dispersion phases such as feal3, mnal6 and cral3 are blocked. The recrystallized grains grow uniformly. However, when heated to high temperature, a few grain boundaries will disperse. Will these particles grow rapidly and form several very large grains as they dissolve and disappear first. In one condition, manganese, chromium and other elements can refine the grain structure, but in another condition, they may promote the secondary recrystallization, so as to obtain thicker or uneven thick structure.
If the recrystallization texture is produced after the recrystallization of 5052 aluminum plate, the "texture braking effect" will be produced. However, there are always a few grains with different orientations in the obviously oriented materials. Right? If these particles are small or equal to the average size, they will be absorbed by the surrounding particles. If the grain size of these orientations is larger than the average grain size, growth will occur and the secondary recrystallization process will begin. The more perfect the original recrystallization texture, the more inhibition of normal growth, the more obvious the secondary recrystallization.
(3) plate thickness
When the grain size of 5052 aluminum plate reaches 2-3 times of the thickness, the normal grain growth stops completely. However, when the surface energy of the free surface (flat surface) of each grain is different, the grains with lower surface energy grow up. Due to the preferred orientation of recrystallized grains in aluminum plate, most of them have similar free surface energy, and only a few grains with certain orientation difference have different surface energy. This small part of grains with low surface energy will become the secondary recrystallization nucleus. It is theoretically proved that the second recrystallization under this condition requires only surface energy difference instead of the grain size larger than the average grain size.
(4) Annealing atmosphere
The free surface energy is related to the surface adsorption, so it is not only related to the annealing temperature, but also to the annealing atmosphere of aluminum plate. Therefore, the same material can be controlled to produce different types of secondary recrystallization by changing the atmosphere. The material is transformed into another secondary recrystallization. This transformation of secondary recrystallization is called tertiary recrystallization. From the phenomenon point of view, the third recrystallization is the combination process of large grains and small grains.
The above is the relevant content introduced by the aluminum plate manufacturer for you. To learn more, please visit the website: http://www.jndclyxgs.com