High Strength hardness Cold Rolled Steel Coil High quality steel for Automotive manufacturing

Hot rolling

Hot rolling takes slab (mainly continuous casting billet) as raw material and makes strip steel from roughing mill and finishing mill after heating. The hot steel strip from the last finishing mill is cooled to the set temperature by laminar flow, and is rolled into steel strip coil by the coiler. The cooled steel strip coil is processed into steel plate, flat coil and longitudinal strip products by different finishing lines (leveling, straightening, transverse or longitudinal cutting, inspection, weighing, packaging and marking, etc.) according to different needs of users. To put it more simply, a slab of steel is heated (the kind of red, hot piece of steel that burns on TV), rolled several times, trimmed, and straightened into a steel plate. This is called hot rolling.

 Cold rolling

Cold rolling: with hot rolled steel coil as raw material, after pickling to remove the oxide skin for cold continuous rolling, the finished product is rolled hard roll, because of the cold hardening caused by continuous cold deformation of the rolled hard roll strength, hardness, toughness and plastic index decline, so the stamping performance will deteriorate, can only be used for simple deformation parts. Hard roll can be used as raw material in hot dip galvanizing plant because hot dip galvanizing units are equipped with annealing line. Rolled hard coil weight is generally 6~13.5 tons, steel coil at room temperature, hot rolled pickling coil continuous rolling. The inner diameter is 610mm.

Product features: Because it has not been annealed, its hardness is very high (HRB is greater than 90), the machining performance is very poor, can only be simple directional bending processing less than 90 degrees (perpendicular to the direction of coiling).

To put it simply, cold rolling is processed and rolled on the basis of hot rolled plate and roll. Generally speaking, it is a process of hot rolling - pickling - cold rolling.

Cold rolling is processed by hot rolled plate at normal temperature, although the steel plate will be heated up during the processing process because of rolling, but still called cold rolling. As a result of hot rolling through continuous cold deformation of cold rolling, the mechanical properties are relatively poor, the hardness is too high. Must be annealed to restore its mechanical properties, not annealed called rolled hard roll. Rolled hard roll is generally used to do without bending, stretching products.