Introduction of hot rolled coil
hot rolled coil are made of slabs (mainly continuous casting slabs) as raw materials, which are heated and made into strips by rough rolling mills and finishing mills.
The hot steel strip from the last rolling mill of the finishing rolling is cooled to the set temperature by laminar flow, and is coiled into a steel coil by the coiler. The finishing line (leveling, straightening, cross-cutting or slitting, inspection, weighing, packaging and marking, etc.) is processed into steel sheets, flat rolls and slitting steel strip products.
To put it simply, after a piece of billet is heated (that is, the red hot steel block that burns on TV), it is refined and rolled several times, then trimmed and corrected into a steel plate. This is called hot rolling.
Due to its high strength, good toughness, easy processing and good weldability and other excellent properties, hot continuous rolled steel sheet products are widely used in ships, automobiles, bridges, construction, machinery, pressure vessels and other manufacturing industries.
With the increasing maturity of hot rolling dimensional accuracy, shape, surface quality and other new control technologies and the continuous advent of new products, hot continuous rolled steel plates and strip products have been more and more widely used and have become more and more powerful in the market. competitiveness.
Hot rolled coil product classification:
Hot continuous rolled steel sheet products include steel strips (coils) and steel sheets cut from them. The steel strip (roll) can be divided into straight hair rolls and finishing rolls (split rolls, flat rolls and slit rolls).
Hot rolled coil production process:
The hot-dip galvanizing hot-rolling plate unit adopts the improved Sendzimir method annealing process, and the raw material is hot-rolled pickling coil. The production process is as follows:
Hot-rolled pickling coil → uncoiling → cutting head and tail → welding → inlet looper → improved Sendzimir method horizontal annealing furnace → hot dip galvanizing → cooling after plating → zinc layer thickness gauge → smoothing and straightening → passivation treatment → Inspection table → Electrostatic oiling → Coiling → Weighing and packing → Finished product storage.
Reasons for dezincification of hot rolled coils
(1) The remaining impurity particles on the surface of the substrate were not removed before being immersed in the zinc pot, which affected the adhesion of the zinc layer.
(2) The iron oxide layer is attached to the substrate, which proves that the substrate is not completely reduced to the spongy pure iron required for galvanizing in the annealing furnace.
(3) The Al content in the alloy layer is small, and a reasonable Fe2Al5 alloy layer that plays a decisive role in the adhesion of the zinc layer is not formed, or the alloy layer is damaged by the overgrown iron-zinc alloy layer.
Based on the above analysis, it is believed that in order to solve the problem of zinc layer peeling off, it is necessary to improve the surface cleanliness of the substrate, ensure the atmosphere control in the annealing furnace, ensure the complete reduction of the substrate, and adjust the temperature of the zinc liquid components. product quality.
Related Reading:
hot rolled coil steel type application
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