What is the reason why the bright annealing furnace is not bright during annealing

The reasons why the bright annealing furnace is not bright during annealing are as follows:

1. Whether the annealing temperature reaches the specified temperature. Bright annealing furnace generally adopts solid solution heat treatment, that is, people usually call "annealing", and the temperature range is 1040 ~ 1120 ℃ (Japanese standard). It can be observed through the observation hole of the annealing furnace. The stainless steel pipe in the annealing area shall be incandescent, but there is no softening and sagging.

2. 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 can not contain too much oxygen and water vapor.

3. Tightness of furnace body. The bright annealing furnace shall be closed and isolated from the outside air; If hydrogen is used as protective gas, only one exhaust port is connected (used to ignite the discharged hydrogen). The inspection method can use soapy water to wipe the joints of the annealing furnace to see whether there is air leakage; The places where gas is easy to escape are the place where the annealing furnace enters and exits the pipe. The sealing ring in this place is particularly easy to wear, so it should be checked and replaced frequently.

4. Protective gas pressure. In order to prevent micro leakage, the protective gas in the furnace shall maintain a certain positive pressure. In case of hydrogen protective gas, it is generally required to be more than 20kbar.

5. Water vapor in the furnace. On the one hand, check whether the furnace body materials are dry. When the furnace is installed for the first time, the furnace body materials must be dried; Second, whether there are too many water stains left on the stainless steel pipe entering the furnace, especially if there are holes on the pipe, do not leak in, otherwise the atmosphere of the furnace will be destroyed. If there are no such problems, the stainless steel pipe that should be retreated for about 20 meters after opening the furnace will start to shine, which is the kind that is bright and reflective.