The hot-rolled coil passes through the pickling line, where the hydrochloric acid solution is used to remove the rust and impurities on the strip surface creating a clean surface before starting the next stage.
The strip after removed rust by pickling line will move into the tandem cold rolling mill (TCM), where they are rolled to a certain thickness. This stage is vitally important to maintain a uniform and accurate flatness throughout the length of the strip. The rolling process is controlled automatically by modern computer technologies.
The main purpose of this process is to remove the rolling oil and remaining impurities on the cold-rolled coil surface before entering the annealing process. Rolling oil on the strip surface is cleaned by mechanical and chemical methods when the strip goes through the Alkaline liquid.
After cold rolling, the strip becomes hard and brittle with the deformation of crystal particles in the rolling direction. To achieve the physical properties of the customer requirements, the strip will put into an Annealing furnace with heating, holding heat and cooling zones. With such diverse heat cycles, that will increase the deep stamping and high strength of the steel. Normally, there are two annealing methods: batching and continuous annealing, in which the annealing line will have superior techologyivity.
FINISHING & INSPECTION
The product’s sizes which are thickness and width, as well as surface quality are controlled during this process. The product’s samples will be transferred to the laboratory for tests, including mechanical, physical, chemical, and etc. The sprayed oil will cover the strip surface to prevent rust happened during storage and delivery.