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topic 25146

Passivation of Stainless Steel after Chrome Plating

adv.     u.s chrome


A discussion started in 2003 & continuing through 2017

(2003)

Q. Dear Readers,

Can I eliminate the passivation treatment of 17-4PH cast stainless steel after heat treatment, at the casting house, if the machined parts are going to be chrome plated? Doesn't the chrome plating process strip off the passivation layer during pretreatment and then re-occur during the final stages of the chrome plating process? Some regions of the part are chrome plated.

Thanks for your response,

Leslie Steele
Aerospace - Greenville, Ohio


(2003)

A. You do not need to passivate the stainless steel casting prior to chrome plating.

Toby Padfield
Automotive suspension modules - Michigan


(2003)

A. Chemical cleaning may be helpful for this process, but passivation is not needed. You are right in that the passive layer will be removed in the activation treatment before plating.

lee kremer
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Lee Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
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August 8, 2016

A. The OP notes that some regions are plated, which I take to mean that some areas will be masked off. If a region is masked off, and thus protected from the bath, I suspect that there will be surface iron that will allow rust spotting more readily than a passivated piece.

Wyndon Evans
- Lago Vista, Texas



August 21, 2017

Q. If there are masked areas that require passivation can it be done after chrome plating?

Ruth Neal
- Farmingdale, New York, USA


August 2017

A. Hi Ruth. Although it might be possible to put chrome plating into a passivating solution with minimal damage, I'm not sure, and it would probably depend on the type and thickness. Hopefully another reader has experience with it. Please explain your actual situation instead of casting the question in the abstract because it strikes me as more practical to passivate the whole item, mask the areas you don't want chrome plated, do the chrome plating, then remove the masking. Good luck.

Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


August 22, 2017

Q. Hi Ted,
Our plater overlooked passivating before plating; we are hoping to avoid having to strip the parts just to ensure a small exposed area has passivation. Thanks for your help!

Ruth Neal [returning]
- Farmingdale, New York, USA


August 23, 2017

A. Ruth,
I don't see why not. You'll have less risk of damaging the chrome using citric passivation rather than nitric passivation.

Chrome plating stainless steel they way you describe seems like a curious thing. Is there any reason it couldn't be mild steel with 100% coverage of the chrome plating, or stainless steel that is electropolished rather than plated?

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