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Electrochemical method for evaluating pitting resistance of stainless steel

A stainless steel, electrochemical technology, applied in the direction of material electrochemical variables, weather resistance/light resistance/corrosion resistance, scientific instruments, etc., can solve problems such as inability to provide accurate evaluation of pitting corrosion, limited number of pitting corrosion, and inability to provide pitting corrosion initiation.

Inactive Publication Date: 2010-06-30
FUDAN UNIV
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Problems solved by technology

The two methods mentioned above are to obtain the critical temperature value or critical potential value at which steady-state pitting occurs in a certain medium, but practice has proved that most of the steady-state pitting pits are above 100 microns, and it is impossible to provide pitting corrosion. Information about initiation, the transition period from initiation to development, and the development process, and after the potential scan or temperature scan is completed, the number of pitting corrosion is limited, which cannot provide accurate information about the occurrence of pitting corrosion

Method used

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  • Electrochemical method for evaluating pitting resistance of stainless steel
  • Electrochemical method for evaluating pitting resistance of stainless steel
  • Electrochemical method for evaluating pitting resistance of stainless steel

Examples

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Embodiment 1

[0025] Example 1 Evaluating the Pitting Corrosion Resistance of 2205 Duplex Stainless Steel

[0026] 2205 duplex stainless steel (1100°C solution treatment for 2h) was encapsulated with epoxy resin, and a surface of 8mm×8mm was left for the experiment after polishing. The specific conditions are: the medium is 1mol / L NaCl solution, and the temperature is maintained at 80°C. The amplitude of the applied rectangular pulse is 500mV, the width is 2s, the period is 12s, and the number of pulses is 30 times (see attached Figure 1~3 ). The result shows as Figure 4~5 shown. The pitting pits generated on the surface of the sample are all distributed in the ferrite phase, with a total of 35±3 pits.

Embodiment 2

[0027] Example 2 Evaluation of Pitting Corrosion Resistance of 304 Austenitic Stainless Steel

[0028] 304 austenitic stainless steel (1100°C solution treatment for 2h) was packaged with epoxy resin and polished to leave a surface of 8mm×8mm for the experiment. The specific conditions are: the medium is 1mol / L NaCl solution, and the temperature is maintained at 60°C. The amplitude of the applied rectangular pulse is 500mV, the width is 1s, the period is 11s, and the number of pulses is 50 times. The results are shown as attached Image 6 shown. The etch pits generated on the surface of the sample are all distributed in the grains.

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Abstract

The invention belongs to the technical field of pitting corrosion evaluation of stainless steel and relates to a method for controlling and evaluating occurrence and development of pitting corrosion of the stainless steel, in particular to an electrochemical method for evaluating pitting resistance of the stainless steel. In the method, by adopting rotary pulse technique, selecting a proper temperature and medium, controlling pulse waveform and the number of pulses and effectively controlling the quantity and the size of pitting corrosion on the surface of the stainless steel, the evaluation of development positions, quantity, size and shape of corrosion pit and the like of the pitting corrosion in the stainless steel is realized. By the method, a large amount of information on the pitting corrosion is qualitatively and quantitatively obtained, and an important basis is provided for the research on the corrosion resistance of the stainless steel, so that the method has great research and application significance.

Description

technical field [0001] The invention belongs to the technical field of pitting corrosion evaluation of stainless steel, and relates to a method for controlling and evaluating the occurrence and development of pitting corrosion of stainless steel. In particular, it relates to an electrochemical method for evaluating the pitting corrosion resistance of stainless steel. Background technique [0002] Pitting corrosion is one of the most common forms of corrosion in passivating metals or alloys. The prior art discloses that stainless steel exhibits good corrosion resistance in many media. However, in some aggressive solutions, such as solutions containing chloride ions, small corrosion pits often occur due to harmful local metal anodic dissolution. - pitting. This type of corrosion has the characteristics of being extremely concealed and destructive. Therefore, its mechanism has always been one of the research focuses of this type of material. At present, the conventional met...

Claims

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Application Information

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IPC IPC(8): G01N17/00G01N27/26
Inventor 蒋益明高娟邓博项秋伟李劲
Owner FUDAN UNIV
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