What are differences between hot rolling and cold rolling of seamless steel pipe

　　The advantages of hot rolling seamless steel pipe are that it can destroy the casting structure of ingot, refine the grain size of steel, and eliminate the defects of microstructure, so that the structure of steel is compact and the mechanical properties are improved.

　　The advantages of cold rolling of DIN2391 St52.3 Cold Rolled Seamless Steel Pipe are: fast forming speed, high output, and no damage to coating, which can be made into various cross-section forms to meet the needs of service conditions; cold rolling can produce large plastic deformation of steel, thus improving the yield point of steel.

　　The main differences between hot rolling and cold rolling of seamless steel pipe are as follows:

　　1. Local buckling of cold-rolled seamless steel pipe section is allowed, which can make full use of the post-buckling bearing capacity of members, while local buckling of hot-rolled seamless steel pipe section is not allowed.

　　2. The causes of residual stresses in hot-rolled seamless steel pipe and cold-rolled seamless steel pipe sections are different, so the distribution of residual stresses in sections is also very different. The distribution of residual stress on the section of cold-formed thin-walled steel is bending, while that on the section of hot-bonded steel or welded seamless steel pipe is thin film.