【The passivation treatment of stainless steel】

Micro-Giant BioEngineering 2003.10.24

1.1  Except for 303 and 303 Se, all 300 series chromium-nickel stainless steels may be used. 20-40% HNO3 (volume concentration), 130-160°F, 30-60 minutes.

1.2 Specifically for use with 303 and 303 Se

20% HNO3 (volume concentration) plus 2% sodium dichromate (weight concentration), 110~130°F, 30 minutes. After taking out and cleaning, do the following treatment. Immerse in 140~160°F, 5% (weight concentration) sodium dichromate solution for 1 hour. After removing, rinse thoroughly in hot water and dry.

2. The passivation treatment of ferritic stainless steel:

2.1 430, 442, and 446 use

20~40% HNO3 (volume concentration), 130~160°F, 30~60 minutes.

2.2 405, 430F, and 430F Se use

20~40% HNO3 (volume concentration), 110~130°F, 30~60 minutes.

2.3 Highly polished 405, 430, 442, and 446 use

50% HNO3 (volume concentration), 90~100°F, 30~60 minutes. After removing, rinse thoroughly in hot water and dry.

3. The passivation treatment of martensitic stainless steel

3.1 403, 410, 414, 420, 431, 440A, 440B and 440C use

At room temperature, 70% HNO3 (volume concentration) for 30~60 minutes, or immersion in 20~30% HNO3 (volume concentration) plus 2% (weight concentration) sodium dichromate or potassium dichromate solution, 70~112°F, 15 to 30 minutes. After removing, rinse thoroughly in hot water and dry.

3.2 16 dedicated

Immerse in 15% (volume concentration) nitric acid, 1-1/2" pounds of sulfuric acid per 10 gallons, 110-125°F, 15-30 minutes. After removing, rinse thoroughly in hot water and dry.

3.3 All martensitic stainless steel can be used

Immerse in 120-130°F, 50% (volume concentration) HNO3 for 5 minutes. After removing, rinse thoroughly in hot water and dry. Note: This quick treatment method can be used for all types of stainless steel without etching concerns.

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