ot-rolled strip steel requirements of SSAW steel pipe: the main control of chemical composition of hot-rolled strip steel is to reduce the carbon content of parathion and phosphorus, and to add appropriate content of titanium, vanadium and niobium. Reducing carbon content can effectively improve the weldability of steel, reducing sulfur content in steel, improving toughness of steel pipe and the only use of crack injection, reducing sulfide accumulation, improving crack resistance of steel, and reducing sulfur content can improve the surface quality of steel strip. It is harmful to the toughness and weldability of phosphorus steel. Compared with other common elements in steel, phosphorus strongly improves the Charpy impact transition temperature, which has a great influence on hardenability. Reducing phosphorus content can directly improve the weldability, because some of the elements in the steel can improve the weldability of phosphorus steel.
The phosphorus content of hot rolled strip is as low as possible.