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At present, domestic manufacturers are generally using the following forms of processing: stainless steel hydraulic joint processing process problems
(1) cold stamping forming;
(2) hot-stamping forming;
(3) oil pressure forming
In the construction, the problems of pipe fitting quality and the solutions are often seen in the jig and sleeve joint in Beijing
For the tee with larger diameter and thicker wall surface metallographic structure, the standard stainless steel quick twist joint adopts the following two forming methods, and the forming time of these two methods generally needs 1 ~ 2 minutes, or even up to 3 minutes.During these minutes, how to maintain a relatively stable temperature is a key problem for the quality of the pipe fitting. If the temperature difference is too large, uneven flow of steel fiber tissue will be caused, especially for the parts with large deformation., the standard stainless steel sleeve joint due to its large plastic deformation, such as the temperature is too low will cause cold hardening phenomenon resulting in brittle welded joint damage.
3. Heat treatment after forming
The final heat treatment after tee forming can significantly improve the mechanical properties of steel.Especially for the processing method is not too advanced tee factory, choose the right heat treatment system and process is particularly important.In gb12459-90 "steel butt welded seamless pipe fittings, it is stipulated that r cold-formed carbon steel pipe fittings shall be normalized or annealed.Then choose which kind of heat treatment, especially choose which annealing system is better, the standard stainless steel pneumatic pipe joint standard has no choice or description, it depends on the manufacturing process to decide.The author believes that no matter which heat treatment system is chosen, the purpose is to improve the mechanical properties of chongqing flamed joint high pipe fitting and increase its strength.In the process of cold extrusion forming, the microstructure of steel will change greatly due to its large plastic deformation, such as;Zonal structure is obvious, grain size is coarse, grain boundary dislocation, interface slip and so on.These structural changes have a great impact on the cutting and performance of steel.To overcome these adverse changes, it is necessary to change the structure thoroughly through heat treatment, to refine the grain size and make the structure even.To achieve this goal, it is necessary to use normalizing or full annealing process in annealing.Many pipe fitting manufacturers don't fully realize this.For some reason, they only conduct annealing treatment to eliminate the stress on the formed pipe parts, which does not fundamentally change the metallographic structure and properties of the pipe parts, so it is difficult to guarantee the quality of the pipe parts.