Continuous annealing and acid washing method for medium-chromium ultrapure ferrite stainless steel

A technology of ultra-pure iron and stainless steel is applied in the new process field of improving the corrosion resistance of medium-chromium ultra-pure ferritic stainless steel. , The effect of meeting the requirements of corrosion resistance and reducing production costs

Active Publication Date: 2013-08-14
SHANXI TAIGANG STAINLESS STEEL CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] In general, the medium-chromium ultra-pure ferritic stainless steel plate for automobile exhaust pipe is 2B plate, and the main process flow of 2B plate production is cold rolling → annealing → cooling → drying → sodium sulfate electrolysis → water washing → nitric acid electrolysis → water Rinsing→chemical pickling→water rinsing→drying→leveling→packing, the chemical pickling process is the final process that affects the performance of the passivation film on the surface of ultra-pure ferritic stainless steel 2B. However, in the actual production process, the existing acid The passivation film on the surface of ultra-pure ferritic stainless steel produced by washing process cannot meet the corrosion resistance requirements of automobile exhaust pipes

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] Example 1 Application of this process on the annealing and pickling production line of 1.5mm thick 00Cr17Mo (436L) stainless steel cold plate

[0016] In the existing continuous annealing and pickling production line, according to the mass ratio, the concentration is 65% HNO 3 , the concentration is 40% HF and water, according to HNO 3 Prepare pickling solution with a ratio of 150g / L, HF 3.5 g / L and the rest water;

[0017] The pickling solution is heated to 40±2°C in the circulation tank, the valve is opened to circulate the pickling solution between the circulation tank and the mixed acid tank, and the production line is started to make the 00Cr17Mo (436L) stainless steel strip run at a speed of TV value 28 (stainless steel strip The residence time in the mixed acid tank is 3min) for annealing and pickling. After the steel strip is rinsed, dried and flattened, samples are taken from the head to evaluate the corrosion resistance of the stainless steel surface.

...

Embodiment 2

[0019] Example 2 Application of this process on the 1.2 mm thick 00Cr17Ti (439) stainless steel cold plate annealing and pickling production line

[0020] In the existing continuous annealing and pickling production line, according to the mass ratio: according to HNO 3 Prepare pickling solution with a ratio of 130g / L, HF 2 g / L and the rest water;

[0021] The pickling solution is heated to 40±2°C in the circulation tank, the valve is opened to circulate the pickling solution between the circulation tank and the mixed acid tank, and the production line is started to make the 00Cr17Ti (439) stainless steel strip run at a speed of 23 (stainless steel strip) The actual residence time in the mixed acid tank is about 3min) for annealing and pickling. After the steel strip is rinsed, dried and flattened, samples are taken from the head to evaluate the corrosion resistance of the stainless steel surface.

[0022] The pitting potential of 00Cr17Ti (439) stainless steel surface in 3.5%...

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Abstract

A continuous annealing and acid washing method for medium-chromium ultrapure ferrite stainless steel comprises the process flow of cold rolling, annealing heat treatment, acid washing, final water washing, drying, flattening and packaging, and is characterized in that in the acid washing process flow, the acid washing solution is prepared from 120-150g/L of 65% nitric acid, 2-4g/L of 40% hydrofluoric acid and water. According to the invention, in the chemical acid washing stage, reasonable concentration ratio of nitric acid to hydrofluoric acid is adopted and proper acid washing speed is controlled to carry out acid washing on medium-chromium ferrite stainless steel. As a result, on one hand, the performance of a medium-chromium ferrite stainless steel passivation film is obviously improved, and the corrosion resistance of the surface of a medium-chromium ferrite stainless steel 2B board is significantly improved, and on the other hand, the process flow of the existing production factory is not needed to be changed, a special passivation treatment procedure is not needed, and the production cost is significantly lowered.

Description

technical field [0001] The invention relates to the surface treatment of the stainless steel plate in the continuous annealing and pickling production process of the stainless steel cold-rolled plate, especially a new process for improving the corrosion resistance of the medium chromium ultra-pure ferritic stainless steel. Background technique [0002] In recent years, the problem of global environmental pollution has aroused great attention from countries all over the world to the automobile exhaust emission system. In many countries, the graded requirements for automobile fuel economy and automobile exhaust emissions are becoming more and more stringent. The traditional cast metal and aluminum-plated carbon steel materials for exhaust systems can no longer meet the requirements. The green environmental protection material stainless steel that meets the 3R requirements is especially high The performance of ferritic stainless steel has been widely used. [0003] The automob...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C23G1/08
Inventor 秦丽雁刘春来范光伟王志斌杨西才邹勇张保亮高登
Owner SHANXI TAIGANG STAINLESS STEEL CO LTD
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