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topic 14291

Pickling of stainless steels like SS304, 316, 310 - HOW?

A discussion started in 2002 & continuing through 2017



Can you advise me on what solution to be prepared for pickling of stainless steel Gr.310, 304 and 316. These grades are investment cast by us. The pickling should bring out the pleasing colour of stainless steels.

Thanking you in advance,

Hemant B. Kamat
- Belgaum, Karnataka State, India


A. Hemant:

You should look at ASTM A380 [link is to the practice at TechStreet] for recommended practices for pickling. If you need to passivate to prevent corrosion, you need to see ASTM A967 [link by ed. to spec at TechStreet] . These grades are quite corrosion resistant, but need to be passivated to obtain the highest chromium content on the surface for optimum resistance.

lee kremer
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Lee Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
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December 10, 2008

A. There are so many different method for pickling of stainless steel.
Triple acid, double acid are use to pickle above grade. You can use HCl+HF+HNO3 acid or HCl+HNO3 or HF+HNO3 acid.

Umashankar Gupta
- Nagpur, India

Staining during pickling and passivation of 304L

February 9, 2017

Q. Good day to all, I am in desperate need of some assistance. We are currently building 304L stainless steel primary settling tanks & bridges. We have noticed that after we pickle and finally passivate there are stain marks that resemble water marks. What are these due to and can they be removed?

Bruno Pinto
Quality Manager - South Africa

February 20, 2017

A. Bruno,
Two possibilities I can think of:

Etching due to over- or underexposure from your pickling and/or nitric acid passivation treatments.

Actual water marks due to rinsing with hard water.

ray kremer
Ray Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
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