Heat-treated workpiece
Although it is not recommended, it still needs to be explained that during the stretching process, due to cold plastic deformation, the workpiece will undergo cold work hardening, which will reduce its plasticity and increase deformation resistance and hardness. In addition, the mold design is unreasonable. Intermediate annealing softens the metal and restores its plasticity.
Note: The general process does not require intermediate annealing. After all, to increase the cost, you must choose between increasing the process and increasing the annealing, use it with caution!
Annealing generally adopts low temperature annealing, that is, recrystallization annealing. There are two things to pay attention to when annealing: decarburization and oxidation. Here we mainly discuss oxidation. After the workpiece is oxidized, oxide scale will be produced. This has two disadvantages: the effective thickness of the workpiece becomes thinner and the wear of the mold is increased.
When the company's conditions are not met, ordinary annealing is generally used. In order to reduce the generation of oxide scale, the furnace should be filled as much as possible during the annealing process. I also used the soil method:
1. When there are fewer parts, it can be mixed with other parts (premise: annealing process parameters should be basically the same).
2. Put the workpiece in the iron box and weld it to the furnace. In order to eliminate the oxide scale, pickling treatment should be carried out according to the situation after annealing.
When the company's conditions are available, nitrogen furnace annealing can be used, that is, bright annealing. If you don't observe carefully, the color is almost the same as before annealing.
When there is no other method to deal with the metal with strong cold work hardening or tensile cracks in the test mold, an intermediate annealing process is added.
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