Four factors affecting the flange process are:
1. Annealing temperature reaches the specified temperature. Flange processing is generally adopted solution heat treatment, temperature range of 1040~1120℃ (Japanese standard). You can also observe through the annealing furnace observation hole, the flange in the annealing area should be incandescent, but there is no softening sagging.
2. Sealing of furnace body. The bright annealing furnace shall be enclosed and isolated from the outside air; With hydrogen as a guard gas, only one vent is open (to ignite the vented hydrogen). The method of inspection can be used to wipe the cracks of each joint in the annealing furnace with soap and water to see whether the air runs away; Among them, the most easy to run air is the annealing furnace into the pipe and out of the pipe place, the sealing ring in this place is particularly easy to wear, often check and often change.
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3. Protect air pressure. In order to prevent micro-leakage of pipe fittings, the protective gas in the furnace should maintain a certain positive pressure. If it is hydrogen protective gas, it is generally required to be above 20kBar.
4. Annealing atmosphere. Generally, pure hydrogen is used as the annealing atmosphere, and the purity of the atmosphere is more than 99.99%. If the other part of the atmosphere is inert gas, the purity can also be lower, but it must not contain too much oxygen and water vapor.