In the production and processing of high-precision cold-drawn pipes, in order to meet better strength and hardness, attention should be paid to the details of each link during annealing and cooling to achieve good results.
Regarding the cooling of this product during production, the technical requirements applied here are very high. If the temperature is not well controlled, thermal stress and structural stress will be generated, which may cause cracks or warping of the steel pipe.
The high-precision cold-drawn tube will deform due to the redistribution of internal stress during machining, which cannot guarantee the machining accuracy. In addition, the processing of large parts is also prone to residual stress. These products require stress relief after rough machining.
When cooling, the surface and some sections often produce white, white and hard and brittle structures, which are not well cut and easy to use when peeled off. Therefore, ordinary products should be annealed to eliminate casting defects. The annealing or normalizing temperature is mostly 850- between 950°C. The temperature is maintained for 1-2 hours, and the cementite is synthesized into graphite and austenite. During the subsequent furnace cooling period, the secondary cementite and eutectoid cementite will again be synthesized into graphite. Thereafter, the matrix of ferrite or ferrite is added with pearlite, thereby reducing the hardness and strength of the casting, if required for wear resistance of the product, heating, insulating without a furnace and using air cooling. In addition to the cement cementation process at 850-950 °C, the cementite synthesis time is cooled during normalization, which can reduce the hardness of the product, and also a pearlite matrix can be obtained, adhering to a specific strength and hardness.
Above, when the high-precision cold-drawn tube is cooled, if you want to produce high-quality products, you must strictly control all aspects.
