Cold drawn (rolled) seamless steel pipe: round tube perforation → heating → → → annealing → pickling → Heading oiled (copper) → multi-pass cold drawn (cold) → blank tube → heat treatment → straightening → water pressure test (testing) → mark → storage.
Hot-rolled (extrusion seamless steel pipe): round tube perforation → → heating → three-roll rolling, rolling or extrusion → detached → sizing (or reducing) → cooling → → straightening → pressure pipe billet test (or testing) → mark → storage.
Detailed process two kinds of steel pipe
Cold drawn steel hot rolled coils as raw materials for cold rolling after pickling descaling, the finished product is rolling hard volumes, due to continuous cold work hardening caused by deformation of the strength of the rolling hard volumes, and increased hardness, toughness plastic index decreases. Accordingly stamping performance will deteriorate and can only be used for simple modification parts. Rolling hard volumes can be used as hot-dip galvanizing plant raw materials.
Usually cold rolling plate, coil should be evaluated by continuous annealing (CAPL unit) or batch annealing and rolling to eliminate work hardening stress, achieve appropriate standards for mechanical performance indicators.
Cold-rolled steel surface quality, appearance, dimensional accuracy are better than hot-rolled sheet, and its right-rolled thin product thickness to about 0.18mm, and therefore the majority of users. Cold rolled coil substrate for the deep processing of products, a high value-added products. Cold-rolled steel coil after annealing must be finishing, including the cutting head, tail, trimming, leveling, smooth, rewind, or longitudinal clipboard and so on. Cold-rolled products are widely used in automobile manufacturing, household appliances, instrument switch, construction, office furniture and other industries.