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Analysis of The Principles of Galvanized Sheet Control
In order to obtain fine and uniform ferrite grains, the process requirements are as follows:
(1) The final rolling temperature should be above A3, and the coiling temperature should be below A. In this way, a uniform and equiaxed fine grain structure and a carbide phase with a high degree of dispersion can be obtained. If the coiling temperature is high, a uniform coarse grain structure will be generated, and at the same time, carbides will accumulate to a considerable extent, which is not good for the performance of the steel plate.
(2) During final rolling and coiling at low temperature below A3, because ferrite has undergone processing deformation, coarse ferrite grains appear on the surface layer, thereby forming an uneven grain structure. If high-temperature coiling is performed under these conditions, A very uneven coarse-grained structure is generated, and the surface grains are extremely coarse.
(3) If the final rolling temperature is lower, the extended ferrite grains will appear and remain in the steel after coiling at low temperature or when recoiling at high temperature, coarse grain structure will be formed due to self-tempering.
In addition: the raw materials used for galvanized sheets produced by China PPGI corrugated roofing sheet manufacturer are mainly rolled slab and continuous casting slab. The thickness of the slab used in the hot rolling mill is generally 150 ~ 300mm, most are 200 ~ 250mm, and the thickest is 350mm. In modern times, the rolling process has been completely canceled to increase the length of the slab and adopt full longitudinal rolling. Therefore, the width of the slab is larger than the width of the finished product. The width of the strip is controlled by the vertical rollers, and its length mainly depends on the width of the heating furnace And required blank weight.