- Time effect elimination method
Aging elimination is a traditional method to reduce quenching residual stress. As aluminum alloy materials, especially aviation aluminum alloy materials, are very sensitive to temperature, the increase of aging temperature will obviously reduce the strength index, resulting in excessive precipitation of mgzn2 and other strengthening phases, resulting in over aging phenomenon. Therefore, aging treatment after quenching is usually carried out at a lower temperature (less than 200-250 ℃), which affects the stress relief effect (only 10-35%)
- Mechanical stretching the principle of mechanical stretching is to apply a certain amount of permanent tensile plastic deformation to the quenched aluminum alloy plate along the rolling direction, so that the plastic deformation will occur after the superposition of tensile stress and the original quenching residual stress, so that the residual stress can be relaxed and released. The results show that more than 90% of the residual stress can be eliminated by mechanical stretching. However, this method is only suitable for the parts with simple shape, and it has high requirements on the microstructure uniformity of aluminum alloy sheet before drawing, so it is mostly used in aluminum processing plants.
- Die cold pressing method
Die cold pressing method is to eliminate the residual stress of aluminum alloy die forgings with complex shape through strictly controlled limited cold shaping in a special finishing die. In fact, the term “die pressing” is not accurate enough, because its main mechanism is to make the local material of aluminum alloy die forgings subject to “tension” or “compression”. When the finishing die is pressed down, the finishing punch is embedded into the draft angle of the end face and edge (rib) of the aluminum alloy die forging, which actually causes the “tensile” effect on the web part of the die forging. Therefore, this method is to adjust rather than eliminate the overall stress level of the parts. It can release the residual stress in some parts of the aluminum alloy die forging and increase the residual stress in other parts.
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