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Annealing and pickling method for duplex stainless steel

A duplex stainless steel, pickling technology, applied in cleaning methods and utensils, chemical instruments and methods, cleaning methods using tools, etc., can solve problems such as being unfavorable to environmental protection and employee health, increasing production costs, and increasing purification and recycling. Achieve the effect of avoiding the use of nitric acid and HF, saving production costs and protecting the environment

Active Publication Date: 2018-12-11
ZHANGJIAGANG POHANG STAINLESS STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage is that the process uses a large amount of HNO in the mixed acid pickling process 3 and HF, and the concentration is high and highly corrosive. In order to increase the production cost of the enterprise, a large amount of waste acid will increase the burden of purification and recovery, which is not conducive to environmental protection and employee health.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] In this embodiment, 329J3L stainless steel with a thickness of 1.8mm and a width of 1240mm is selected for annealing and pickling. The strip is annealed in a horizontal continuous annealing furnace, pickled, smoothed, and finished after coiling, wherein the furnace heating section is 100m long; sodium sulfate electrolysis The total length of the section is 90m; the total length of the grinding and scrubbing section is 6 meters, and the length of the mixed acid section is 72m. Pickling includes neutral salt electrolysis, abrasive scrubbing and mixed acid pickling to remove scale.

[0030] In the annealing stage, the duplex stainless steel is annealed in a furnace at a temperature of 1090 ° C for about 133 seconds.

[0031] In the sodium sulfate electrolysis stage, the duplex stainless steel enters the 64-meter and 26-meter sodium sulfate electrolytic cells twice respectively, and the first sodium sulfate electrolysis is completed in the 64-meter-long first sodium sulfate...

Embodiment 2

[0036] In this embodiment, 329J3L stainless steel with a thickness of 1.5mm and a width of 1240mm is selected for annealing and pickling. The strip is annealed in a horizontal continuous annealing furnace, pickled, smoothed, and finished after coiling, wherein the furnace heating section is 100m long; sodium sulfate electrolysis The total length of the section is 90m; the total length of the grinding and scrubbing section is 6 meters, and the length of the mixed acid section is 72m. Pickling includes neutral salt electrolysis, abrasive scrubbing and mixed acid pickling to remove scale.

[0037] In the annealing stage, the duplex stainless steel is annealed in a furnace at a temperature of 1075 ° C for about 133 seconds.

[0038] In the sodium sulfate electrolysis stage, the duplex stainless steel enters the 64-meter and 26-meter sodium sulfate electrolytic cells twice respectively, and the first sodium sulfate electrolysis is completed in the 64-meter-long first sodium sulfate...

Embodiment 3

[0043] In this embodiment, 329J3L stainless steel with a thickness of 1.0mm and a width of 1240mm is selected for annealing and pickling, and the strip is annealed in a horizontal continuous annealing furnace, pickled, smoothed, and finished after coiling, wherein the furnace heating section is 100m long; sodium sulfate electrolysis The total length of the section is 90m; the total length of the grinding and scrubbing section is 6 meters, and the length of the mixed acid section is 72m. Pickling includes neutral salt electrolysis, abrasive scrubbing and mixed acid pickling to remove scale.

[0044] In the annealing stage, the duplex stainless steel is annealed in a furnace at a temperature of 1060 ° C for about 133 seconds.

[0045] In the sodium sulfate electrolysis stage, the duplex stainless steel enters the 64-meter and 26-meter sodium sulfate electrolytic cells twice respectively, and the first sodium sulfate electrolysis is completed in the 64-meter-long first sodium sul...

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PUM

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Abstract

The invention discloses an annealing and pickling method for duplex stainless steel. The method comprises the following steps that the duplex stainless steel subjected to cold rolling through a twenty-high roll mill is uncoiled, degreased, annealed in a continuous annealing furnace, pickled, leveled and coiled so as to obtain a finished product, wherein in the annealing step in the continuous annealing furnace, the annealing temperature is 800-1200 DEG C, the pickling step comprises the processes of primary sodium sulfate electrolysis, primary grinding and scrubbing, secondary sodium sulfate electrolysis, secondary grinding and scrubbing and mixed acid pickling, and scale is removed through the pickling step. The method has the advantages that the pickling step after annealing of the duplex stainless steel comprises the processes of twice neutral salt sodium sulfate electrolysis, twice grinding and scrubbing and mixed acid pickling, so that the scale on the surface of strip steel is removed, the concentration of HF used is low, the operation time is short, the production cost is saved, the safety of workers is protected, and the environment is protected.

Description

technical field [0001] The invention belongs to the technical field of duplex stainless steel smelting, and in particular relates to a cold annealing and pickling method for duplex stainless steel. Background technique [0002] Duplex stainless steel refers to stainless steel in which ferrite and austenite each account for about 50%, and generally the content of less phases needs to reach at least 30%. In the case of low C content, the Cr content is 18-28%, and the Ni content is 3-10%. The traditional duplex stainless steel (such as 329J3L) cold rolling annealing pickling production process is annealing, salt bath, sodium sulfate electrolysis, mixed acid pickling (HNO3, HF). The main purpose of annealing is to soften the rolled and work-hardened stainless steel through recrystallization by heating. After cold annealing of duplex stainless steel, an oxide scale is formed on the surface, and its main components are oxides of Fe and Cr; salt bath The ingredients used are NaOH...

Claims

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Application Information

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IPC IPC(8): C25F1/06C23G1/08B08B1/00C21D9/56C21D1/26
CPCB08B1/002C21D1/26C21D9/56C23G1/086C25F1/06
Inventor 张华年章礼喜熊元泉孙玉磊
Owner ZHANGJIAGANG POHANG STAINLESS STEEL
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