Need to passivate (430 or 430F/430FR???)
Need to passivate (430 or 430F/430FR???)
(OP)
Let me start off by saying I’m not a metallurgist, I’m a chemical engineer. I have a metallurgist problem though! I bought a stainless steel stock pot, which has some small rust spots/streaks on the bottom after an hours-long soak in tap water. I understand I need to re-passivate it. The manufacturer of the pot told me it’s 18/0 steel, which I think means it’s the same as 430. I have the chemicals (nitric acid and NaOH) needed to passivate it, but I don’t know if its 430 or 430F/FR. There are different passivation methods for the two, correct?
How can I tell? Will it hurt to be safe and follow the NaOH regimen with 430, even though it doesn’t need it?
Thanks in advance for your help!
How can I tell? Will it hurt to be safe and follow the NaOH regimen with 430, even though it doesn’t need it?
Thanks in advance for your help!





RE: Need to passivate (430 or 430F/430FR???)
For passivation process, see HOW TO PASSIVATE STAINLESS STEEL PARTS from Carpenter Techn.: http://
This article shows a hex. chrome passivation for 430 (same as well as for 430F), Type II per QQ-P-35C, but QQ-P-35C Types VII or VIII can be used as well. Some people use the Type VIII solution (hot nitric) for 430F although not per spec.
QQ-P-35C http:
It won't hurt 430 to be passivated per the procedure for 430F involving the extra alkaline steps.
For optimal corrosion resistance, the smoother the surface the better. Prior to the passivation process, remove the stains & buff the surface using SimiChrome or similar. It leaves a film, so degrease before further processing.