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Effect of annealing treatment on surface brightness of stainless steel butt welded elbow

The factors that affect the brightness of stainless steel butt welded elbow during annealing, and the brightness of the product after annealing determines the quality of the product. There are many factors that affect its brightness, including five important factors

1. Whether the annealing temperature reaches the specified temperature or not, the heat treatment of stainless steel butt welded elbow generally adopts solution heat treatment, which is called "annealing", and the temperature range is "1040 ~ 1120 ℃ (Japanese standard)". After the investigation of annealing furnace, the stainless steel butt welding elbow in annealing zone should be incandescent, but there is no softening sling sagging.
2. The annealing atmosphere generally adopts pure hydrogen as the annealing atmosphere, and the purity of the atmosphere is more than 99.99%. If another part of the atmosphere is inert gas, the purity can be lower, but it can not contain too much oxygen and water vapor.
3. The furnace body shall be sealed and bright light annealing furnace shall be closed and isolated from the outside air; if hydrogen is used as maintenance gas, only one exhaust port is open (used to ignite the discharged hydrogen). The way to check is to wipe soapy water on the joints of the annealing furnace to see if there is gas leakage. The place where the annealing furnace enters the pipe and the place where the annealing furnace goes out of the pipe are the places where the gas is easy to escape. The local sealing ring is particularly easy to wear, so it should be checked and replaced frequently.
4. Maintenance gas pressure in order to prevent micro leakage, the maintenance Gas in the furnace should be kept at a certain positive pressure, and hydrogen maintenance gas should be added, generally more than 20kbar.
5. On the one hand, check the water vapor in the furnace to see if the furnace data is dry, and the furnace data must be dried for the first time; on the other hand, check whether the stainless steel pipe entering the furnace has too much water stains, especially if there are holes in the pipe, do not leak in, otherwise the furnace atmosphere will be completely destroyed.
Generally, if it is normal, the stainless steel tube that should be retreated about 20 meters after the furnace is opened will start to shine, which can be noticed when we leave the factory.

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