What is the purpose and requirements of stainless steel welded pipe bright annealing
The bright annealing furnace is mainly used for the heat treatment of the stainless steel welded pipe under the protective atmosphere. When the requirements of using performance are not the same, the requirements on the microstructure of the bright annealing is different, bright heat treatment process is also different. 300 series austenitic stainless steel pipe typical heat treatment process is solid solution treatment. In the heating process in the carbide dissolve in austenite, heated to 1050~1150℃, appropriate thermal insulation for a short time, which make carbides are dissolved in austenite, and then cooled rapidly to 350℃, obtain supersaturated solid solution is uniform one-way austenite. What is the purpose and requirements of stainless steel bright annealing, the heat treatment process is the key to rapid cooling, the cooling rate required to reach 55℃/s, fast through the carbide solution after the re precipitation temperature zone (550~850℃). Heat preservation time should be as short as possible, otherwise the coarse grain, affecting the surface finish.
400 series ferritic stainless steel heating temperature is relatively low (about 900 degrees), and more use of slow cooling to obtain annealing and softening. Martensitic stainless steel can also be used in the way of subsection quenching and tempering.
bright annealing furnace
Stainless steel welded pipe
From the above shows that the 300 series and 400 series of stainless steel in the heat treatment system is very different, to get qualified metallurgical organization, it requires a bright annealing furnace cooling section of the equipment which has a lot of room for adjustment. Therefore, the modern advanced bright annealing furnace, the cooling section is often used in strong convection cooling, three cooling sections, can be individually regulated air volume. Stainless steel bright annealing for what purpose and requirements, along the strip width direction and three section, through air flow diversion regulation in the strip width direction of the cooling rate, the control plate.
Another key problem of heat treatment of cold rolled stainless steel welded pipe is to require the whole strip to be uniform in width and length. Muffle type bright annealing furnace with the large size of the muffle tube, from the muffle tube external evenly tissue heating air flow spiral around and make the strip is heated uniformly. To ensure that the strip along the length of the direction of the organization, it is to keep the strip in the heating furnace in the same line speed. Therefore, in the modern vertical bright heat treatment furnace is equipped with a precision adjustment of the roller type tension adjustment device. It is not only the strip import and export speed to meet the requirements of heat treatment speed and from the live set amount of empty set or a full set of effects, and according to the plate strip establishment and adjustment precision steel strip small tension, meet the requirements of the plate.
At the same time how to maintain the purity of the gas in the furnace is also need to be paid attention to. On this, muffle good sealing performance, does not occur, such as electric heating furnace material to protect the atmosphere pollution, as compared to the pristine environment of space. In addition, the vertical furnace strip out of the entrance are located at the bottom of the furnace, the furnace pressure stability, and thus compared with the horizontal furnace, the air into the risk of much smaller. But the bright annealing furnace of import and export seal box, the strip steel delivery, a tension adjusting roller and top guide roller box should ensure to achieve the sealing requirements of parts per million (ppM) and to oxygen and water vapor can not enter, protective gas can not leak out.
stainless steel welded pipe
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