Process characteristics of hot dip galvanized flat steel
1. The reliability is relatively good, the durability of galvanized is high, and it is a part of the steel surface.
2. The cost is relatively low, lower than the cost of painting.
3. It can save time and effort, and the construction is more convenient, avoiding the waste of time after the device is painted on the site.
4. Toughness is relatively strong, and it can avoid mechanical damage during transportation.
5. Complete maintenance, each part should be galvanized.
Refining steps of hot dip galvanized flat steel
The first step of iron smelting: the main raw material of blast furnace iron smelting is iron ore, its main component is iron oxides, such as Fe2O3, Fe3O4 and so on. At the same time, coke is used as a reducing agent and heat source, limestone as a flux, these materials are added from the upper part of the blast furnace, and the preheated air is blown into the lower part, so that the coke burns, producing a lot of heat, and the high temperature is reached in the high brain, and the iron ore is reduced into hot metal and molten slag, respectively, from the bottom.
The second step of steelmaking: the carbon content of the molten iron from the blast furnace is higher, and it contains more harmful elements such as phosphorus and sulfur, which must be smelted. Now the molten iron from the blast furnace is transported to the steelmaking factory by torpedo tank car, poured into the converter or electric furnace, and then added a certain amount of scrap steel, at the same time adding slag making agent, continue heating, so that the scrap steel is also melted, and constantly blowing oxygen into the furnace, so that the carbon oxidation in the molten iron is removed, and the phosphorus, sulfur and other harmful elements in the molten iron are removed, and then the chemical composition is properly adjusted to obtain molten steel. Molten steel becomes slab after continuous casting and cooling by continuous casting machine.
The third step is hot rolling of the hot galvanized flat steel galvanizing line: the slab is sent into the hot rolling furnace to heat, and then into the hot rolling line. The continuous hot rolling line generally first carries out the forging of the slab to remove phosphorus, and then carries on the reciprocating rolling extension, when the length of the slab reaches a certain degree, it begins to enter the continuous rolling process, after several continuous rolling processes, it is rolled into the thickness of 2.0-3.5mm hot rolled steel strip black roll. The fourth step is to pickling the galvanized line of hot-dip galvanized flat steel: the surface of the hot-rolled steel strip is covered with a layer of oxide, which has a complex structure and must be removed on the pickling line. Before pickling, phosphorus is generally broken by bending and stretching to remove large areas of oxide. In pickling, the oxidation film is mostly removed by reaction of hydrochloric acid aqueous solution with iron oxide after heating. After three-stage pickling, the residual acid stains are removed by three-stage washing. The edge is cut on the pickling line at the same time, and the bad part on the edge of the hot rolled plate is cut off, and the width of the steel coil is controlled accurately within the specified range.
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