Cold rolling and hot rolling are two different steel rolling technology, as the name implies, cold rolling is to tie steel at room temperature, the hardness of this steel is large. Hot rolling is when steel is tied together at high temperature.
1. Hot rolled
The continuous casting slab or raw rolled slab is used as raw material, heated by stepping heating furnace, descaled by high pressure water and then entered the roughing mill. The roughing material enters the finishing mill after cutting head and tail, and the computer is implemented
Controlled rolling, after the final rolling, laminar cooling (computer controlled cooling rate) and coiler reel, become straight coil. The head and tail of straight hair curls are often tongue-shaped and fish-shaped.
The width accuracy is poor, and the edge part often has defects such as wave shape, folding edge and tower shape. The coil is heavy and the inner diameter of the steel coil is 760mm. (The general pipe industry likes to use.) Cut straight curls through the end,
Cutting tail, cutting edge, straightening, leveling and other finishing line treatment, then cutting or rewinding, namely: hot rolled steel plate, flat hot rolled steel coil, sash and other products. Hot rolled finish roll is hot rolled pickling plate roll after pickling removing the oxide scale and oiling. The product has a partial alternative to the trend of cold rolled sheet, moderate price, loved by the majority of users.
The hot rolled steel coil is used as raw material, after removing the oxide scale by pickling, the finished product is rolled hard coil. Due to the cold working hardening caused by continuous cold deformation, the strength and hardness of rolled hard coil increase, and the toughness and plastic index decrease, so the stamping performance will deteriorate, and can only be used for simple deformation parts. Hard roll can be used as raw material for hot-dip galvanizing plant, because hot-dip galvanizing units are set to retire
The line of fire. The weight of rolled hard coil is generally 6~13.5 tons, and the inner diameter of steel coil is 610mm.
Generally, continuous annealing (CAPL unit) or cover furnace annealing should be used to eliminate cold work hardening and rolling stress, so as to achieve the mechanical properties specified in the corresponding standards.
The surface quality, appearance and dimensional accuracy of cold-rolled steel plate are better than that of hot-rolled steel plate, and the thickness of cold-rolled steel plate is about 0.18mm, so it is favored by the majority of users. Cold-rolled steel coil is used as base plate for deep processing of products, and it has become a high value-added product. Such as galvanized, hot dip galvanized, fingerprint galvanized, color coated steel coil and vibration absorption composite steel plate, PVC
Coating steel plate, so that these products have beautiful, high corrosion resistance and other excellent quality, has been widely used. Cold-rolled steel coil must be finished after annealing, including cutting head, tail, cutting edge, leveling, leveling, rewinding, or longitudinal shearing plate. Cold rolled products are widely used in automobile manufacturing and home appliances
Products, instrument switches, construction, office furniture and other industries.