The essence of the concept of "metal annealing" is the behavior of several operations. First, the metal is heated, holding at a certain temperature. This is followed by air or oven cooling. By the way, vacuum annealing usually requires more expensive equipment.
Metal annealing can be a final technological operation or an intermediate one. Usually, annealing refers to heat treatment, which includes the process of heating steel to certain temperatures, holding at these temperatures and subsequent cooling. By the way, the temperature is usually determined by the purpose of the annealing.
How is annealing of metals carried out?
It is customary to produce several types of annealing of metals: diffusion, full, low and annealing to granular perlite. Different types of annealing serve different purposes. Perhaps annealing is necessary to eliminate chemical heterogeneity in cast parts, to crush grain that has increased in the course of previous operations. Also, annealing of metals may be required to relieve internal stresses and lower the hardness of metals.
Diffusion annealing is performed to equalize the chemical composition of steel ingots. This is possible due to the diffusion of elements. After such annealing, the steel usually becomes uniform in composition. In another way, such an operation is called homogenization. Select the highest possible temperature for this type of annealing. Otherwise, diffusion will not be efficient. Heating is carried out up to three hundred degrees. In this case, the annealing exposure is from twelve to fifteen hours, followed by cooling. By the way, the cooling should be slow enough.
The total duration of the process can last from eighty to one hundred hours. After such annealing, the structure of the metal is significantly leveled in chemical composition. True, the metal acquires a coarse-grained structure.
Annealing of the first and second kind
Homogenization or diffusion annealing can be classified as type I annealing. Also, annealing of the first kind includes the formation of a new metal structure after processing under high pressure. This process is called recrystallization annealing of metals.
As for the annealing of the second kind, it can be associated with cardinal changes in the structure of metals. With the help of annealing of the second kind, it is possible to achieve changes in the mechanical properties of metals. Often, such annealing is used for steels, cast irons, non-ferrous metals and various alloys. When carrying out annealing of the second kind, the phase diagrams for a particular metal alloy must be taken into account.
