Low acid consumption anti-corrosion hot-replacing-cold product production method

Abstract

The invention relates to a low acid consumption anti-corrosion hot-replacing-cold product production method. The low acid consumption anti-corrosion hot-replacing-cold product production method comprises the following steps: uncoiling by adopting an uncoiler; breaking and stripping oxide on the surface of strip steel by adopting a temper mill; further breaking and stripping the oxide on the surface of the strip steel by adopting a multi-roll straighter; eliminating the oxide which falls off and is loose on the surface of the strip steel by adopting a brushing device; carrying out acid pickling and rinsing on the treated strip steel; then eliminating residue on the surface of the strip steel by adopting a mechanical way; carrying out surface roughness homogenization finishing on the strip steel; recoiling by adopting a recoiler. By virtue of the technical scheme, the low acid consumption anti-corrosion hot-replacing-cold product production method has the advantages that firstly more cracks and large gaps are formed in the oxide on the surface of the strip steel, so that acid pickling efficiency is high; secondly, eliminating part of oxide while breaking scale, so that acid picking reacting dose is reduced, and acid consumption is reduced; thirdly, added value of yield strength of the strip steel after processing is low; fourthly, a Luders strip is avoided from being formed on the surface of a common hot rolling product; fifthly, chlorine ion residue on the surface of a product is reduced, and corrosion resistance of the product is improved.

Description

technical field [0001] The invention belongs to the field of deep processing of ordinary hot-rolled flat materials, and in particular relates to a production method of low acid consumption and corrosion resistance by substituting heat for cold products. Background technique [0002] The average production cost of cold-rolled products is 1,000 yuan / ton of steel higher than that of hot-rolled products. In order to reduce production costs, people continue to explore the use of certain surface treatment methods to replace some cold-rolled products with hot-rolled products, usually at the outlet of the pickling unit. The first tempering machine improves the surface quality of pickling products and meets the demand of replacing cold with heat. [0003] Such as figure 1 As shown, this type of unit has the following salient features: it is composed of an uncoiler 1, an inlet looper 2, a tension leveler 3, pickling 4, a rinse 30, an outlet looper 5, a skin pass machine 22, and a coi...

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Problems solved by technology

[0003] like figure 1 As shown, this type of unit has the following salient features: it is composed of an uncoiler 1, an inlet looper 2, a tension leveler 3, pickling 4, a rinse 30, an outlet looper 5, a skin pass machine 22, and a coiler 6. The tension leveler 3 is configured to mechanically break phosphorus, and the strip steel after the phosphorus breakdown becomes a hot-rolled pickling product after pickling 4 and rinsing 20, and a skin pass machine 22 is arranged at the exit of the unit to improve the surface quality of the pickling product. There are the following defects in the production process. The phosphorus breaking effect is not ideal, which leads to low efficiency of pickling 4; acid residue after pickling 4 is serious, which reduces the corrosion resistance of the product

[0004] like figure 2 As shown, the main reason for the low efficiency and high acid consumption of pickling 4 is that there is a contradiction between the phosphorus breaking principle of the tension leveler 3 and the requirement to maintain product performance. 8 Under the action of tensile stress and bending stress, oxide cracks 9 that are consistent with the width direction of the strip steel are formed. After passing through the tension leveler 3, the strip steel 7 recovers elastically, so that the oxide cracks 9 already formed on the surface of the strip steel 7 are closed

[0005] like image 3 As shown, in order to improve the efficiency of pickling 4, it is necessary to set the elongation of the tension leveler 3 above the yield limit of the strip 7, so that the strip 7 produces plastic deformation. After leveling machine 3, the gap of surface oxide 8 can be partially maintained, and the efficiency of pickling 4 can be improved; but the performance loss of the product is serious. For conventional hot-rolled sheets with carbon, nitrogen and other interstitial atoms content ≥ 30ppm, after tension leveling, there will be 7 produces uneven surface yield, commonly known as Lüders band 10; for high-strength steel and IF steel, although Lüders band 10 will not be produced on the surface of strip 7, the yield strength increases with the increase of elongation Unidirectional increase, therefore, increasing the elongation will undoubtedly deteriorate product performance

[0006] After strip steel 7 passes through pickling 4, there will be acid solution residue on the strip steel 7 surface, and the strip steel 7 with poorer surface quality, the greater the surface acid solution residue, these residual chloride ions will seriously corrode the strip steel 7 surface , so that the surface of steel strips is yellow or yellow-green spots, and these strips are not as bright as normal strips after rolling, and the finished products are prone to re-corrosion

[0007] In order to reduce acid residue, the strip steel 7 is traditionally cleaned by multi-stage rinsing 30 , and the rinsing temperature is continuously increased during the rinsing 30 , increasing the kinetic energy of molecules in the rinsing 30 tank, and accelerating the acid diffusion. The rinsing temperature is about 85°C, which increases the energy consumption of the production process. Even so, from the actual production situation, the acid concentration in the final rinse 30 tank is still 100mg / l-150mg / l

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