Cold rolling: hot rolled coil 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 raw material for hot-dip galvanizing plant, because hot dip galvanizing line is provided with annealing line. Rolling hard volumes generally weighs 6 to 13.5 tons of steel coils at room temperature, the volume of hot pickling continuous rolling. An inner diameter of 610mm.

Cold rolling at room temperature, is machined from hot-rolled plates made, although the process also makes steel rolling because warming was nevertheless called cold rolling. By the continuous hot rolling after cold deformation from the cold rolling, relatively poor mechanical properties, hardness is too high, it must be annealed to restore its mechanical properties without annealing called rolling hard volumes. Rolling hard volumes generally used to do without bending, stretching products, rolling hard thickness of 1.0 or less lucky on both sides or four sides bent.

Chemical composition :

Cold rolling production process

Cold-rolling and commonly used way. Cold rolling production process generally include raw material preparation, pickling, rolling, degreasing, annealing (heat treatment), finishing and so on. Cold to hot-rolled products as raw materials, cold raw material before first removal, to ensure that the surface of the cold rolled products clean. Rolling the material deformation is the main step. The purpose is to be attached to skim grease rolled on the rolling is removed, to prevent pollution of the steel surface during annealing, but also to prevent the stainless steel by carbon. Annealing including intermediate annealing and final heat treatment, the intermediate annealing is through recrystallization work hardening produced eliminate cold deformation, to recover plastic material and reduce the deformation resistance of the metal. Finished purpose of heat treatment except through recrystallization eliminate hardening outside. In that according to the technical requirements for products to obtain tissue (such as a variety of texture, etc.) and the desired product properties (such as deep drawing, electromagnetic properties, etc.). Finishing includes inspection, shear, straightening (flat), printing, packaging and other content classification. Cold-rolled products have a high packing requirements, to prevent product during transport surface is scratched. The step when external production of some special products in addition to each have their own special process. As time rolled silicon steel sheet before cold rolling to decarburization annealing, after rolling to conduct film, high-temperature annealing, stretching straightening (see tension straightening) and tempering.

Cold-rolled grades available

Rolling mill for cold-rolled strip has a two-roll mill, four-high mill and the cluster mill. The most widely used four-roll mill. Rolled thinner product will have to adopt a multi-roll mill. Many types of multi-roll mill, such as the six-high rolling mill, roller mill partial eight, twelve roll mill, twenty roll mill, etc. (see mill). With the improvement of the flatness requirements, we developed many improved flatness of techniques, such as bending technology, technology and cross roll technology channeling rolls. Cold rolling strip mill per rack arrangement can be divided into single reversible or irreversible type and continuous multi-machine categories. The former applies to more variety, small batch or alloy steel products case large scale. Its low investment, quick construction, but low yield, large consumption of metal. Multi-stand continuous rolling product varieties more suitable for single or little change in the situation, it has a high production efficiency, yield advantages, but a larger investment. And hot rolled strip (see hot rolling wide strip steel production technology, production of hot rolled narrow strip) compared to cold rolled strip (see cold-rolled strip production) of the rolling process has the following characteristics: (1) using the process of lubrication and cooling to reduce deformation resistance and the cooling roll during rolling; (2) using a large tension rolling, to reduce deformation resistance and stable rolling process. The average unit value of the materials used tension yielding 10% to 60% strength, generally not more than 50%; (3) multi-rolling process rolling. Because of cold rolled to produce material hardening, when the total amount of deformation of 60% to 80%, it becomes difficult to continue deformation. To do this intermediate annealing, after the rolled material is softened to proceed. In order to get thin strip requirements, intermediate annealing so it may take several. Rolling between the two intermediate annealing is called a rolling process. Annealed cold-rolled strip steel in a protective gas continuous annealing furnace or annealing furnace is performed (see cold-rolled strip annealing). The minimum thickness of cold-rolled strip current can reach 0.05mm, cold-rolled foil can reach 0.001mm.

Mechanical Properties