Dear Tai,

I would suggest you first count the pits on a defined surface area and sum up the area they occupy. Additionally you should prepare a metallographic cross section and measure the depth of the pits. Only the depth is related to the intensity of the attack. One deep pit can cause more damage than some shallow pits.

Regards

Alexander

Hi,

regarding electrochemistry you will maybe find something useful in the following paper:

G. S. Frankel

Pitting Corrosion of Metals

J. Electrochem. Soc., Vol. 145, No. 6, 2186-2198 (1998)

Especially on page 2187 findings from electrochemical studies are presented!

Hope this helps. Best regards

Dear Tai,

there are several standards which give guidance for electrochemical pitting tests of stainless steels. The most popular ones are:

ASTM G61 Cyclic Polarization Test

ASTM G150 Electrochemical Pitting Temperature Test

Which one you may use depends on the required conclusion out of the test.

Dear Tai

I would recommend the cyclic polarization test.   Please refer to the following article:

-Habib, K. ,"In-situ monitoring of pitting corrosion of copper alloys by  holographic interferometry",Corrosion Science,Vol. 40, No. 8, PP.1435(1998).

The paper combines both an electrochemical test, i.e., cyclic polarization test, and an optical technique,i.e., holographic interferometry, for in situ monitoring of pitting corrosion of copper alloys.

Mr.Tai Jen Seng, I suggest for you to go through the electrochemical noise measurement technique in pitting corrosion monitoring.

Best regards

Many materials are susceptible to pitting corrosion, but the important thing is the service conditions. The most common way is by doing a cyclic polarization test. Pitting is dependent of the material and the electrolyte conditions. Make sure you know your environment and the material you want to test, do not forget to compare the result to control sample (this might be a different material that is already in service).

For measuring the pitting potential of any metal you can use the cyclic polarisation and potentiostatic test. these are the short term electrochemical tests and give the instant results. For long term test you can use the immersion test or weight loss method. after removing the metal sample from immersion solution you can calculate corrosion rate and under microscope you can observe pits and pit depth.

Hi there, 

Simply, you can use the cyclic polarisation at high scan and enhancement the results with ESM images or use the EFM technique.

Regards,