Annealing of Hollow Sections
Date:2022-03-07View:547Tags:Hollow sections
Hollow sections can greatly save machining time, improve material utilization, and help improve product quality. Compared with ordinary pipes, hollow sections have higher dimensional accuracy and better surface finish.
Annealing method of hollow section:
1) Hollow section annealing can maintain bright appearance and dimensional accuracy, and annealing of cold-rolled strips with no surface oxidation and no decarburization in a protective atmosphere. There is a single inert gas argon or helium in the protective atmosphere, which can adjust the composition of these mixed gases, so that the redox, decarburization, and carburization rates are equal during the annealing process of the strip, and the annealing of the strip without oxidation and decarburization is realized;
2) After annealing, there is an invisible oxide film on the surface of the hollow section to protect the metallic luster. According to the chemical reaction between furnace gas and steel and the influence of its development and change, the environmental protection working atmosphere is prepared and applied, and the conditions for preventing oxidation and decarburization are determined.
Tips:due to the poor thermal conductivity of the hollow section, the heating rate should not be too fast, otherwise melting defects and some quenching cracks will appear. In order to reduce the quenching deformation, the deformation of the hollow section due to its slenderness must be strictly controlled; heat treatment is a very important process. In the process of quenching and cooling, the use of cold plasticity for timely correction is the key process to ensure the improvement of the pass rate. Therefore, hot bath quenching or cooling should be carried out in oil for a certain period of time. In order to reduce the quenching deformation, the high-precision guide rail should be gas nitrided or ion nitrided to reduce the deformation.
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