Beryllium bronze is a kind of precipitation-hardening alloy with very wide use. The strength can reach 1250-1500mpa (1250-1500 kg) after solution and aging treatment. Its heat treatment characteristic is: After the solid solution treatment has the good plasticity, may carry on the cold processing deformation. However, after aging treatment, it has excellent elastic limit, while the hardness and strength are also improved.
(1) Solid solution treatment of beryllium bronze
The heating temperature of the general solution treatment is between 780-820 ℃, and the material used as the elastic component is 760-780 ℃, which is mainly to prevent the coarse grain from affecting the strength. The temperature uniformity of solution treatment should be strictly controlled in ±5℃. Heat preservation time can generally be calculated according to 1 hours/25mm, beryllium bronze in the air or oxidizing atmosphere in the solution heat treatment, the surface will form oxide film. Although it has little influence on the mechanical properties of the aging hardening, it will affect the service life of the die during cold working. In order to avoid oxidation should be in the vacuum furnace or ammonia decomposition, inert gas, reducing atmosphere (such as hydrogen, carbon monoxide, etc.) heating, so as to obtain a bright heat treatment effect. In addition, we should also pay attention to shorten the transfer time (this quenching), otherwise it will affect the mechanical properties after aging. The thin material must not exceed 3 seconds, and the general parts shall not exceed 5 seconds. Quenching medium generally uses water (no heating requirements), of course, the shape of complex parts in order to avoid deformation can also be used oil.
(2) The aging treatment of beryllium bronze
The aging temperature of beryllium bronze is related to the content of be, and the alloy containing be less than 2.1% is suitable for aging treatment. For the alloy being greater than 1.7%, the optimum aging temperature is 300-330 ℃, and the holding time is 1-3 hours (according to the shape and thickness of the part). For a highly conductive electrode alloy less than 0.5%, the optimum aging temperature is 450-480 ℃ and the Heat preservation time is 1-3 hours due to the melting increase. In recent years, has also developed a two-stage and multi-stage aging, that is, the first in the high temperature short time, and then at low temperature long time insulation aging, the advantage is that the performance is improved but the deformation is reduced. In order to improve the dimensional accuracy after the aging of beryllium bronze, fixture clamping can be used for aging, and sometimes two separate aging treatment can be used.
(3) The stress treatment of beryllium bronze
Beryllium bronze to stress annealing temperature of 150-200 ℃, holding time of 1-1 5 hours, can be used to eliminate the metal cutting, straightening treatment, cold forming and other residual stresses, stable parts in the long-term use of the shape and size accuracy.
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