Seamless pipe are roughly divided into cold forming and hot forming.Here are the differences between cold forming and hot forming.
Seamless pipe, a round, square, rectangular steel with a hollow cross-section and no seams around, are roughly divided into cold forming and hot forming. Most standard seamless pipes can be made with these two processes, such as ASTM A53, ASTM A500,ect. Hot rolling is hot working, and cold drawing is cold working. So what are the differences between cold drawn steel pipe and hot rolled steel pipe?
The main difference: hot rolling is rolling above the recrystallization temperature, cold rolling is rolling below the recrystallization temperature; cold rolling may sometimes be heated, but the temperature is relatively low, because the cold rolling will produce processing Hard, if the requirements for the molding of the material are relatively high, it must be annealed.
Cold rolled and hot rolled are generally plates or profiles, while cold drawn are generally cylindrical cross-section wires. In addition, hot-rolled sheet is generally a steel with high alloy content and high strength, while cold-rolled steel is low-carbon and low-alloy steel. Cold rolling can increase the strength and ensure the surface quality of the material.
Cold drawn (rolled) pipe are divided into circular pipe and special-shaped pipe:
Cold drawn steel pipe generally need to be drawn multiple times, and there must be corresponding stress relief annealing between each drawing to ensure the smooth progress of the next cold drawing. From the appearance, cold-rolled seamless steel pipe is often of small diameter, and hot-rolled seamless steel pipe is often of large diameter. The precision of cold-rolled seamless steel pipe is higher than that of hot-rolled seamless steel pipe, and the price is higher than that of hot-rolled seamless steel pipe. Cold drawn seamless tubes generally have a small diameter, mostly below 127mm, especially the precision of cold drawn seamless pipe' outer diameter is very high, the length of cold drawn seamless pipe is generally shorter than hot rolled seamless pipe. In terms of wall thickness, cold drawn seamless pipes are more uniform than hot rolled seamless pipe.
