No registration or passwords; no pop-up ads -- just aloha, fun, & answers.
(as an eBay Partner & Amazon Affiliate earns from qualifying purchases).
Home /
T.O.C.
Fun
FAQs
Good
Books
Ref.
Libr.
Advertise
 
Help
Wanted
Current
Q&A's
Site 🔍
Search
pub  Where the
world gathers for metal finishing
Q&As since 1989



-----

Citric Passivation of 440C stainless steel




April 3, 2008

I have a very strange problem that I cannot solve and I would appreciate any comments or feedback :-

I but a 440C stainless steel ball that has been citric passivated.
The ball is boil tested , in boiling water for 4 hours. The water strength is 12 ohms. the balls are always 2" below surface of water to prevent any oxidation. These parts never fail.

My customer then repeats the test using 18 ohms water (all else the same) , but we then have isolated marks on the surface.

These marks look like small rusts spots , by when SEM is done there is no Iron ?

Does anyone have any ideas or comments ?

I am really desperate for help or comments.

Nick Price
Customer of plated products - Pelsall , West Mids , UK



Of course, it is impossible to have "rust" without iron, so if the SEM shows no iron, it could possibly be a sulfide bloom. I have not seen this with 440C, but I do not know what else it would be IF in fact there is no iron in the spot.

My first thought, given all of the facts, is that it is an inclusion on the surface.

lee kremer
lee kremer sig
Lee Kremer
Stellar Solutions, Inc.
supporting advertiser
McHenry, Illinois
stellar solutions banner
April 9, 2008




(No "dead threads" here! If this page isn't currently on the Hotline your Q, A, or Comment will restore it)

Q, A, or Comment on THIS thread -or- Start a NEW Thread

Disclaimer: It's not possible to fully diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations might be harmful.

If you are seeking a product or service related to metal finishing, please check these Directories:

 
Jobshops
Capital
Equipment
Chemicals &
Consumables
Consult'g, Train'g
& Software


About/Contact  -  Privacy Policy  -  ©1995-2024 finishing.com, Pine Beach, New Jersey, USA  -  about "affil links"