During cold drawing, the steel pipe passes through a mold of a certain shape and size under the action of force, and plastic deformation occurs. At present, the drawing methods in production can be roughly divided into three types: reduced-diameter drawing, reduced outer wall drawing and reduced inner wall drawing. During cold drawing, the steel pipe is subjected to drawing force, positive pressure and friction. Corresponding deformations mostly go through the three stages of diameter reduction, wall reduction and sizing, and corresponding stresses are generated in the deformation zone. The axial direction is tensile stress, the radial and circumferential directions are compressive stresses. The metal is in one direction during the process of drawing. Tension and two-way compression stress state, which are the basic mechanical characteristics of the deformation process of cold drawn pipes.
The cold-drawn tube is work hardened. During cold drawing, the metal undergoes plastic deformation, multiple slip systems inside the crystal are activated, and the dislocation movement intercepts each other, and many dislocations are pinned, causing dislocation accumulation, and the dislocation source stops moving at the same time. The above-mentioned series of processes lead to a decrease in the mobility of dislocations and a significant increase in the dislocation density in the crystal. When the plastic deformation further occurs, the stress increases and is enough to make the pinned dislocations start to move, the screw dislocations slip, and the edge dislocations cannot slip, so that the dislocations are intersected and the immovable order increases.
Cold drawn steel pipes are produced at a relatively low temperature. Because of the various tasks and production and processing methods of cold drawn steel pipes, there are many advantages. What are the basic procedures and processes for producing cold drawn square pipes? (1) Pipe material supply, the pipe materials used are hot-rolled finished pipes or semi-finished pipes, extruded pipes and welded pipes; (2) Pipe material preparation, including inspection , Bundling, pickling, cleaning, rinsing, neutralization, drying, lubricant coating, etc.; (3) cold processing (cold rolling or cold drawing); (4) finished product finishing includes finished product heat treatment, straightening, sampling, cutting Head and tail, inspection (manual inspection and various flaw detection), hydraulic test, oiling, packaging, storage, etc. The finishing content of different products is different. This kind of production has improved the performance and various advantages of cold drawn steel pipes.
https://www.skivingtubelw.com
