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Corrosion of Stainless Steel

2002

Dear sir, it is very much pleasing to visit through your website, very much informative since I am in steel ball manufacturing the information published on this website. My problem is :

We are in manufacturing of steel balls, I am getting a problem of corrosion of stainless steel 420 in 2% nitric acid tests, salt spray test after polishing. The heat treatment is done on 1015 °C and tempered at 180 °C the carbon content is 0.25 - 0.45%, Cr = 12 to 14% rest all contents as per std. specification. Can you please help me through since I shall be grateful to you.

Thank you, yours sincerely,

Budhisagar Naik
steel balls - Mumbai, Maharashtra, India

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2002

Budhisagar:

420 "stainless" steel is very difficult to passivate, at best. However, you can get fairly good results with proper treatment of hardened 420. We are not sure what you mean by "2% nitric acid test, salt spray after polishing". 2% nitric acid would be very bad on 420ss. Did you mean 20%?

Best results that we get are by soaking parts in high pH alkaline (we can recommend specific materials) followed by passivation in a citric acid proprietary formulation. You can also use nitric acid for this if necessary- as long as it is done properly. You will not get the same result, however.

Lee Kremer
Stellar Solutions, Inc.

McHenry, Illinois

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Budhisagar:

We have conducted several tests for 420 stainless steel. So far we found out that the best way to passivate this type of stainless steel is through high-voltage process in safe proprietary salty electrolyte. Treated metal stands passivation tests. Depending on time treated the passivating film will be of different level: transparent if treated 1-3 minutes, slightly colored if treated longer. Of course, if you treat stainless steel longer, the passivating film will be thicker, and protection is higher.

Anna Berkovich
Russamer Lab

Pittsburgh, Pennsylvania

2002