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A kind of pickling method of hot-rolled 304 austenitic stainless steel

A technology of austenitic stainless steel and pickling, which is applied in the field of pickling of hot-rolled 304 austenitic stainless steel, can solve the problems of easy clogging of acid pipelines, affect the circulation of acid solution, affect the quality of pickling, etc., so as to increase the efficiency of pickling. , the effect of reducing emissions and reducing production costs

Active Publication Date: 2018-07-24
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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  • A kind of pickling method of 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 a hot-rolled 304 austenitic stainless steel pickling method, comprising a pretreatment step, a sulfuric acid pickling step, a first mixed acid pickling step, a second mixed acid pickling step and a third mixed acid pickling step, Wherein the mixed acid solution used in the above-mentioned three-stage mixed acid pickling step is a mixed pickling solution of nitric acid and fluosilicic acid. The present invention adopts the mixed acid pickling solution of nitric acid+fluorosilicic acid, and H2SiF6, like HF, has strong dissolution and erosion ability to scale and metal matrix, which can increase the pickling efficiency. During the pickling process, the activity of the acid solution remains basically unchanged, which increases the service life of the acid solution, reduces the discharge of waste acid, and reduces production costs and water treatment costs. In the mixed acid pickling solution, fluoride precipitation will not be generated, pipelines will not be blocked, and the number of maintenance shutdowns will be 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 Patents(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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