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Acid pickling method for hot rolled 304 Austenitic stainless steel

A technology for pickling of austenitic stainless steel, which is applied in the field of pickling of hot-rolled 304 austenitic stainless steel, can solve the problems of affecting the quality of pickling, easily clogging acid pipes, affecting the circulation of acid solution, etc., so as to increase the efficiency of pickling , reduce emissions and increase service life

Active Publication Date: 2015-11-04
WISDRI ENG & RES INC LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In addition, as the pickling time prolongs, the fluoride precipitate formed will adhere to the surface of the strip and affect the pickling quality, and will also deposit in the pipeline and circulation tank of the circulation system, which will easily block the acid pipeline and affect the acid solution. cycle; and the peeled off scale on the surface of the strip will combine with fluoride precipitation to form hard sludge, which is difficult to remove, resulting in the need for frequent shutdowns for maintenance

Method used

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  • Acid pickling method for hot rolled 304 Austenitic stainless steel

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Embodiment 1

[0041] This embodiment provides a hot-rolled 304 austenitic stainless steel pickling method, comprising the following steps:

[0042] 1) The hot-rolled 304 austenitic stainless steel strip with a thickness of 2 mm is annealed and mechanically broken.

[0043] 2) Pre-pickling the steel strip after annealing and mechanical scaling treatment by immersing in sulfuric acid pickling solution. In the sulfuric acid pickling solution, H 2 SO 4 The concentration is 155g / L, and the metal ion concentration is 33 g / L; the temperature of the sulfuric acid pickling solution is 77°C; the pickling treatment time is 33s.

[0044] 3) After pickling with sulfuric acid, the steel strip is immersed in the first mixed acid solution for pickling. In the first mixed acid solution, HNO 3 Concentration is 77g / L, H 2 SiF 6 The concentration is 12 g / L, the metal ion concentration is 37 g / L, the temperature of the first mixed acid solution is 57° C., and the pickling treatment time is 33 s.

[0045]...

Embodiment 2

[0049] This embodiment provides a hot-rolled 304 austenitic stainless steel pickling method, comprising the following steps:

[0050] 1) The hot-rolled 304 austenitic stainless steel strip with a thickness of 2 mm is annealed and mechanically broken.

[0051] 2) Pre-pickling the steel strip after annealing and mechanical scaling treatment by immersing in sulfuric acid pickling solution. In the sulfuric acid pickling solution, H 2 SO 4 The concentration is 165g / L, and the metal ion concentration is 37 g / L; the temperature of the sulfuric acid pickling solution is 83°C; the pickling treatment time is 27s.

[0052] 3) After pickling with sulfuric acid, the steel strip is immersed in the first mixed acid solution for pickling. In the first mixed acid solution, HNO 3 Concentration is 83g / L, H 2 SiF 6 The concentration is 18 g / L, the metal ion concentration is 43 g / L, the temperature of the first mixed acid solution is 63°C; the pickling treatment time is 27s.

[0053] 4) Aft...

Embodiment 3

[0057] This embodiment provides a hot-rolled 304 austenitic stainless steel pickling method, comprising the following steps:

[0058] 1) The hot-rolled 304 austenitic stainless steel strip with a thickness of 2 mm is annealed and mechanically broken.

[0059] 2) Pre-pickling the steel strip after annealing and mechanical scaling treatment by immersing in sulfuric acid pickling solution. In the sulfuric acid pickling solution, H 2 SO 4 The concentration is 160g / L, and the metal ion concentration is 35 g / L; the temperature of the sulfuric acid pickling solution is 80°C; the pickling treatment time is 30s.

[0060] 3) After pickling with sulfuric acid, the steel strip is immersed in the first mixed acid solution for pickling. In the first mixed acid solution, HNO 3 Concentration is 80g / L, H 2 SiF 6 The concentration is 15 g / L, the metal ion concentration is 40 g / L, the temperature of the first mixed acid solution is 60° C., and the pickling treatment time is 30 s.

[0061]...

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Abstract

The invention relates to an acid pickling method for hot rolled 304 Austenitic stainless steel. The acid pickling method comprises the steps of pretreatment, sulfuric acid pickling, mixed acid pickling for a first section, mixed acid pickling for a second section and mixed acid pickling for a third section. A mixed acid solution used in the steps of acid pickling for the three sections is formed by mixing nitric acid and fluorosilicic acid. According to the acid pickling method for the hot rolled 304 Austenitic stainless steel, the mixed acid solution formed by mixing nitric acid and fluorosilicic acid is adopted, H2SiF6 has a high ability to dissolve and corrode scale cinder and a metal matrix as HF, and therefore the acid pickling efficiency can be improved. In the acid pickling process, the activity of the acid solution is basically constant, and the service life of the acid solution is prolonged; in this way, the discharge amount of waste acid is reduced, and production cost and water treatment cost are reduced. In the mixed acid pickling process, fluoride sediment will not be generated, a pipeline will not be blocked, and the halt maintenance frequency is reduced.

Description

technical field [0001] The invention belongs to the field of cold-rolled stainless steel production, and in particular relates to a pickling method for hot-rolled 304 austenitic stainless steel. Background technique [0002] At present, mixed acid (HNO 3 +HF) pickling process, however, during the pickling process, as the reaction proceeds, the concentration of metal ions in the solution is getting higher and higher, and the metal ions will interact with F - Ions combine to form fluoride precipitates, resulting in F in solution - The reduction of ion concentration reduces the activity of the mixed acid solution, reduces the pickling efficiency of the mixed acid, shortens the service life of the acid solution, and increases the amount of waste discharged from the acid solution, resulting in an increase in production costs. Moreover, the cost of subsequent water treatment will also increase, this is because F - Ions can prevent the decomposition of nitric acid solution, whil...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23G1/08
Inventor 李勇华贺立红尚志广胡斯尧
Owner WISDRI ENG & RES INC LTD
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