Knowledge of vacuum annealing technology for Nonferrous Metals

Commonly used non-ferrous material annealing usually includes: copper, lead, zinc, aluminum, magnesium, etc. Suzhou jinruier electric furnace Xiaobian takes vacuum annealing of brass and aluminum alloy as an example to explain.

Although the annealing application of nonferrous metal materials is not much, it is necessary to explain it. The commonly used non-ferrous metal materials annealed are: copper, lead, zinc, aluminum, magnesium, etc. annealing in vacuum furnace can achieve good results such as no oxidation decarburization, degreasing and degassing, material purification, etc. High melting point active metals such as button, tungsten, copper, qinhecuo and copper alloys are widely used. When silicon steel sheet is annealed in annealing furnace, the impurity that hinders grain growth can be removed and the magnetic property can be improved. Vacuum annealing in copper wire drawing process can make lubricant volatilize and get smaller surface roughness. Annealing in vacuum can remove oxygen, hydrogen and nitrogen which cause brittleness. Annealing in vacuum can also reduce the deformation due to the small temperature difference between the inside and outside of the workpiece.

Brass annealing:

Taking the annealing of vacuum annealing furnace for brass as an example, the equipment that can be used are water sealed furnace, bell type furnace, tube type furnace, well type vacuum annealing furnace, etc. However, some equipment can not guarantee the quality of the annealed alloy, there is surface oxidation, need pickling. If annealing in protective atmosphere is adopted, the product cost will be increased due to the large amount of atmosphere.

Annealing of aluminum alloy:

The annealing of aluminum alloy can be divided into several types: homogenization annealing, stress relief annealing, recrystallization annealing, product annealing and so on. The box type annealing furnace is mainly used to eliminate the stress, 175 ℃ for 8 hours; the recrystallization annealing temperature is 320-350, the preset temperature is 320, the timing starts after reaching the temperature, and then it is cooled with the furnace, about 60 ℃ for 2 hours.

The purpose of aluminum alloy annealing is to reduce the hardness and improve the elongation. The blank is used for reverse kneading at room temperature.

Processing technology: heating to 510 degrees, holding for 5 hours, then cooling with furnace, cooling temperature less than 10 degrees per hour. Cool to 200 ℃ and get out of the furnace.

When vacuum annealing is used, the heating speed is slow and the energy consumption is large; what is more difficult to control is the dezincification phenomenon on the surface, which reduces the product quality and quality. The advantages of vacuum annealing are as follows

1. The higher annealing temperature, the more dezincification in the same vacuum furnace;

2. The more dezincification, the greater the decrease of tensile strength, hardness and elongation;

3. Increasing furnace pressure can prevent dezincification during annealing.

Through the above description, the brass was annealed in protective atmosphere of vacuum annealing furnace, and good results were obtained. The method is to raise the vacuum annealing furnace to a certain temperature through an electric heater, and put ammonia decomposition gas into the protective atmosphere for annealing. In this way, not only the advantages of vacuum heating (bright surface) are maintained, but also the disadvantages of dezincification and slow heating speed in vacuum state are avoided. The tensile strength deviation of H65 Wire Annealed in vacuum protective atmosphere at the same heat is only within 10 ~ 20MPa, the plasticity is improved, and the elongation deviation is reduced from 10% to 3%.