The characteristics and process flow of cold processing of steel pipe

Cold processing of steel pipe includes cold rolling, cold drawing, cold tension reducing and spinning, etc. It is the main method of producing precision thin wall and high strength steel pipe. Among them, cold rolling and cold drawing are the commonly used efficient production methods for cold processing of steel pipes.

Compared with hot-rolled steel pipes, cold processing of steel pipes has the following advantages:
1. Steel pipe cold processing can produce large diameter thin-wall pipe; High precision of geometric dimensions; High surface finish; Contribute to grain refinement, with the corresponding heat treatment, can obtain higher comprehensive mechanical properties:
2. Steel pipe cold processing can produce a variety of special shape and special section steel pipe. It can process some materials with narrow thermal working temperature range, low toughness at high temperature and good plasticity at room temperature.
3. The outstanding advantage of cold rolling steel pipe is the strong wall reduction ability. The properties, dimensional accuracy and surface quality of the material can be significantly improved.
4. The pass reduction rate of steel pipe cold drawing is lower than that of cold rolling, but the equipment is simpler, the tool cost is less, the production is flexible, and the product shape specification range is also larger.
5. The rational use of cold rolling and cold drawing methods, such as cold tension reduction in recent years, cold processing of welded pipes, and ultra-long pipe cold drawing processes, can improve the output of the unit. Expand the range of varieties and improve the quality of welds.

In addition, temperature processing has received much attention in recent years, usually induction heating to 200-400℃, so that the plasticity of the tube blank is improved. The maximum elongation of warm rolling is about 2-3 times that of cold rolling. The shrinkage rate of the warm drawing section is increased by 30%, so that some metals with low plasticity and high strength are also possible to be finished.
Cold steel pipe processing shortcomings
Although the specification range, dimensional accuracy, surface quality and organizational properties of cold-processed steel pipes are superior to those of hot-rolled steel pipes, there are four problems in their production: many processing cycles, long production cycles, large metal consumption, and complex intermediate treatment processes.

The general process flow of cold rolling and cold drawing of carbon steel pipe and alloy steel pipe is as follows:

1) Pre-cold processing, including preparation of size, shape, microstructure and surface state;

2) Cold processing, including cold drawing, cold rolling and spinning;

3) Finished product finishing, including finished product heat treatment, cutting, straightening and testing.