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topic 4001

Metal Parts are Nickel Plated but are still RUSTING

A discussion started in 1999 but continuing through 2019

1999

Q. One of the products my company offers is called safety clamps, for use with oilfield piping, and they are constantly exposed to the weather. These safety clamps are made from cast 8630 steel. Currently, we have specified a .0005 - .001" electroless nickel plated finish. However, we are running into severe rust/corrosion problems. I understand that going to a thicker plate,~.003", would probably mitigate some of the problems. We originally cast a stainless steel but the CA-6NM stainless that we used, while it resisted rust excellently, didn't give us adequate mechanical properties. When we switched to 17-4PH SS, we got the mechanicals but the parts rusted terribly.

I am a mechanical designer and have very little knowledge in this area. I know that one of you finishing experts could probably easily show me the error of my ways. Does anyone have any suggestions. (i.e. powder coating or ?)

Thanks for your time.

Glenn Hayes
- Ft. Worth, Texas


1999

A. Increasing your EN to 0.0015 minimum should take care of most of your problems.

Also shifting to a higher phosphorous content will help greatly. You probably are using a mid P of 5-7 %. Try increasing to a minimum of 9 with 10 or 11 being even better if you can get it for a reasonable cost including shipping.

Finally, try to find out what metal it is in contact with and what the environment is. If it is in contact with steel that is rusting, it will also rust. If it is in a marine atmosphere, hot and slightly acid it will also rust faster.

James Watts
- Navarre, Florida


1999

A. Hi Glenn,

your problem might be as simple as using the correct specification...

For the 8630 steel , the proper specification would call for Wood's Nickel Strike before electroless Nickel. The Electroless Nickel should have a minimum thickness of 1.5 thousands of an inch, but it MUST be Hi Phosphorous Nickel (approx. 12 % Phosphorous); for some extra protection you could coat the Electroless Nickel with a minimum of 50 Millionths of an inch of Hard Chromium Deposit .

For the 17-4PH S/S the simple answer may be to electropolish the S/S , there by enriching the surface in Nickel & Chrome by selectively removing the Iron and at the same time "Passivating" the enriched Nickel / Chrome surface .

Best regards

John Tenison-Woods
John Tenison - Woods
- Victoria Australia



Nickel Plating rapier hilt to Prevent Rust

2001

Q. I have a rapier hilt that I fight with and it will build up rust very quickly. I have heard that electroless nickel plating can help prevent rust. How much abuse can this plating take and is there something more durable than nickel plating?

James Suttle
- Portland, Oregon


2001

A. There are many ways to prevent corrosion, but nickel plating will probably look the best. Electroless nickel specifically can be made very hard and durable. I suggest you take the hilt over to a local electroless nickel plater and have them give you a quote. The cost will be high, but you should get it professionally done.

tim neveau
Tim Neveau
Rochester Hills, Michigan



Why would 1018 steel rust and pit after being nickel plated?

May 3, 2013

Q. I have a machine shop and we recently made some parts out of 1018 ground steel. We drilled
a hole through the rod to make little tubes 5/8 long by 7/16 diameter. We gave them to our customer who in turn had them nickel plated. I was told after the steel was plated, rust came through the plating and pitted the steel. The nickel was stripped off and I received them back a grey color with a whitish haze over all of the parts. What happened? Why did the parts rust pit and why would they now be grey in color? What can be done to prevent this in the future?

David Olsen
machine shop owner - Cinnaminson, New Jersey, USA


May 7, 2013

A. Hi David. Take a moment and think of a steel ship which is equipped with zinc anodes to keep the hull from corroding. The zinc is more "active" than the steel, so when corrosive forces threaten to attack the steel, electrons flow from the zinc to the steel; thus the steel is preserved while the zinc atoms lose electrons and corrode away as zinc ions.

Lowes bath accessories rusting
Caveat emptor! Big box stores are selling you Chinese nickel-chrome plated hotel shelves & toilet frames that are rusting & pitting before you even buy them.

Now picture your steel parts with a thin and porous or pinholed nickel plating on them. Steel is more active than the nickel, so when corrosive forces threaten to attack the nickel, electrons flow from the steel to the nickel; thus the nickel is preserved while the areas of steel exposed through the pinholes lose electrons and corrode away into pitted rust. Poor nickel plating is far worse than no plating at all as it greatly accelerates rusting.

It would only be a guess as to exactly why the steel parts from which the nickel has been stripped are now gray with a white haze -- something to do with the stripping process and/or a smut from acid cleaning -- but it's unimportant, and you probably did nothing wrong. A plating shop may or may not be able to replate these parts satisfactorily, but that has to be their call whether they are salvageable or over-etched. Good luck.

Regards,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
finishing.com - Pine Beach, New Jersey



May 7, 2013

A. Unless there is something missing in your post, If you have certs for the 1018 steel and the customer accepted them and they had them plated, then the problem is theirs and not yours.
1018 steel is a "low" grade steel that has many uses. If rust is a problem, then the customer should shift his spec to one of the stainless steels.

If he sticks with the 1018, then he should have over 0.0015 electroless nickel put on it. 0.002 would be much better. At this point 316 SS rather than 1018 becomes a better choice in my mind.

James Watts
- Navarre, Florida



Rusting On Iron parts after Nickel Plating

October 30, 2019

Q. We are having problem of rusting of Mild Steel wire hooks. Earlier we used to do surface cleaning after putting the material in caustic soda water barrel and running it for 7-8 hours. Now we have started using centrifugal machine for surface cleaning. We use a cleaning / descaling chemical along with some white deburring powder. We do this for about 40-50 mins then we wash the material and put it on water till the time we put it in nickel plating tank. As if we keep it in open air then it changes it color to yellowish/blackish tone which is may be due it comes in contact with the humid atmosphere.
For your information our nickel plating tank has 18-20 kg nickel plate. We put 50 kg of these small wire hooks at a time and run it for 60 mins in nickel plating. Temperature of water we maintain at around 50-60 degree.

Alok Jain
- Delhi, India


October 2019

A. Hi Alok. Parts must be properly cleaned & activated before nickel plating. Unless I have misunderstood you, you are attempting to go directly from mechanical deburring and a long rinse/hold station to nickel plating without activation. At the least, you need a dip in HCl followed by a rinse after this holding period.

Regards,

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


November 1, 2019

Q. Thanks for your reply. After doing surface cleaning we do rinse the hooks in HCL and then wash it with water before we put it in the nickel plating tank.
Also we want to share with you that we are using hot corn cob dryer for the drying process. Is it ok?
Can you suggest that we shall store the material in water for long (max 2-3 hours) after doing surface cleaning before we put it in nickel plating tank?

Alok Jain [returning]
- Delhi, India


November 2019

A. Hi again Alok. As you have noted, the process used to work until you changed the pretreatment, so the first assumption has to be that the new pretreatment process is not satisfactory. Of course it is not ideal to "store" parts between cleaning and plating, either in or out of water, but ...

As mentioned, my first guess is that the main problem is that the surface is not active when the parts enter the plating tank, so let me emphasize the word that I think you may have glossed over: "At the least you need a dip in HCl followed by a rinse *after* this holding period". Good luck.

Regards,

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

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