For the differences between hot rolled seamless steel pipe and cold drawn seamless steel pipe, mainly in the following aspects:
Processing method: hot rolling is heat treatment method, while cold drawing is cold treatment.
Appearance characteristics: cold rolled seamless steel pipe has a more polished surface, diameter size is smaller than hot rolled steel pipe. While the outer diameter of hot rolled steel pipe is larger than cold rolled steel pipe in most cases, and the surface has oxidized skin or red rust.
Precision and price: The precision of cold rolled steel pipe is higher than that of hot rolled, and its price is correspondingly higher.
Application areas: hot rolled steel pipe is commonly used in liquid transportation and less strict size requirements of the mechanical structure, while cold rolled steel pipe is more suitable for high-precision requirements of the instruments, hydraulic systems and pneumatic parts. In terms of wall thickness, cold drawn steel pipes are usually more uniform than hot rolled steel pipes.
The manufacturing process is as follows:
Hot-rolled seamless steel pipe: starting from round billet → heating → piercing → three-roll slant rolling, continuous rolling or extrusion → removing oxidized skin → fixing the diameter (or reducing the diameter) → cooling → molding → straightening → hydrostatic test (or flaw inspection) → marking → storage.
Cold-drawn or cold-rolled seamless steel pipe: starting from round billet → heating → piercing → first processing → annealing → pickling → oiling (or copper plating) → undergoing several cold-drawn or cold-rolled → molding → heat treatment → straightening → hydrotesting or flaw inspection → marking → storage.
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