At present, domestic manufacturers generally use the following methods for processing and forming: Processing method of stainless steel hydraulic joints

(1) Cold stamping;
(2) Hot stamping forming;
(3) Hydraulic forming



Quality problems and solutions of pipe fittings often seen in ferrule joints during construction
The metallographic structure of the inner and outer walls of the tee is for the tee with larger diameter and thicker wall, the latter two forming methods are mostly used, and the forming time of these two methods generally takes 1 to 2 minutes, and even some can be up to 3 minutes. During these few minutes, how to keep the temperature relatively stable is a key issue for the quality of the pipe fittings. If the temperature difference is too large, the flow of the steel fiber structure will be unbalanced, especially for the parts with large deformation. Because of its large plastic deformation, if the temperature is too low, it will cause cold hardening phenomenon and produce brittle welded joints.






Heat treatment after forming
The final heat treatment after tee forming can significantly improve the mechanical properties of steel. Especially for the manufacture of tee joints with less advanced processing methods, it is especially important to choose the correct heat treatment system and process. In GB12459-90 "steel butt-welded seamless pipe fittings, it is stipulated that the cold-formed carbon steel pipe fittings should be normalized or annealed. So which heat treatment to choose, especially which annealing system to choose is better, there is no standard in the standard. The choice or description depends on the manufacturing process. No matter which heat treatment system is selected, the purpose is to improve the mechanical properties of the pipe fittings and increase their strength. During the cold extrusion forming process of the pipe fittings, the structure of the steel is Due to its large plastic deformation, it will produce great changes, such as: obvious band structure, coarse grains, grain boundary dislocation, interface slip, etc. These changes in structure have a great impact on the machining and performance of steel. It has a great influence. In order to overcome these unfavorable changes, the changed structure should be completely changed by heat treatment, so that the grains are refined and the structure is uniform. To achieve this purpose, it is necessary to use normalizing or annealing medium The complete annealing process is realized. Many pipe manufacturers do not fully realize this. For some reason, they only perform annealing heat treatment for stress relief on the formed pipe, and this annealing does not fundamentally It is difficult to ensure the quality of the pipe fittings by changing the metallographic structure and performance of the pipe fittings.