Seamless steel pipe production, cold rolled VS hot rolled
1. Different manufacturing processes
Hot-rolled seamless steel pipes are heated to high temperatures and then rolled, and are made through multiple processes such as perforation, pipe rolling, cutting, and cooling. Cold-rolled seamless steel pipes are rolled through cold rolling mills and made through multiple processes such as pickling, phosphating, saponification, and lubrication. Therefore, hot-rolled seamless steel pipes have coarser grains and have a certain toughness, while cold-rolled seamless steel pipes have finer grains and have higher strength and hardness.
2. Different dimensional accuracy
Due to different manufacturing processes, there are also differences in the dimensional accuracy of hot-rolled seamless steel pipes and cold-rolled seamless steel pipes. Hot-rolled seamless steel pipes have low dimensional accuracy, uneven pipe wall thickness, and large deviations in pipe diameter and wall thickness. The cold-rolled seamless steel pipe has higher dimensional accuracy, uniform pipe wall thickness, and smaller deviations in pipe diameter and wall thickness. Therefore, cold-rolled seamless steel pipes are usually used where high-precision dimensions are required, such as in petrochemical, pressure vessel and other industries.
3. Different mechanical properties
There are also differences in the mechanical properties of hot-rolled seamless steel pipes and cold-rolled seamless steel pipes. Since the manufacturing process of hot-rolled seamless steel pipes is relatively simple, its tensile strength and yield point are relatively low, while cold-rolled seamless steel pipes have higher tensile strength and yield points due to multiple processes. In addition, hot-rolled seamless steel pipes have better impact toughness, while cold-rolled seamless steel pipes have poor impact toughness. Therefore, cold-rolled seamless steel pipes are usually used where high strength and hardness are required, such as machinery manufacturing, building structures and other industries.
4. Different corrosion resistance properties
There are also differences in the corrosion resistance of hot-rolled seamless steel pipes and cold-rolled seamless steel pipes. Due to the presence of defects and oxide layers on the surface of hot-rolled seamless steel pipes, their corrosion resistance is relatively poor. Cold-rolled seamless steel pipes have been processed through multiple processes, resulting in higher surface smoothness and better corrosion resistance. Therefore, cold-rolled seamless steel pipes are usually used where corrosion resistance is required, such as in chemical, petroleum and other industries.
5. Different uses
There are also differences in the uses of hot-rolled seamless steel pipes and cold-rolled seamless steel pipes. Because the manufacturing process of hot-rolled seamless steel pipes is relatively simple and its price is relatively low, it is widely used in construction, machinery manufacturing and other fields. Cold-rolled seamless steel pipes are widely used in petrochemical, pressure vessels, machinery manufacturing and other fields due to their high strength, high hardness, corrosion resistance and other excellent properties.
To sum up, there are obvious differences between hot-rolled seamless steel pipes and cold-rolled seamless steel pipes in terms of manufacturing process, dimensional accuracy, mechanical properties, corrosion resistance and uses. When choosing to use it, you need to choose the appropriate seamless steel pipe type according to actual needs and usage occasions.
