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topic 47178

Hard Chrome Plating needs more Salt Spray Test hours

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A discussion started in 2007 but continuing through 2019

2007

Q. We have a mechanical assembly used for outdoor applications. Base material is Mild Steel. Operations are press work and machining. It is hard chrome plated to 10 to 15 microns. Could anyone help to know how many hours of salt spray test it would with stand. Suggestions for alternates are welcome. The application is commercial so cost is a big factor. Plating should withstand at least 100 to 120 hours of salt spray for corrosion resistance.

Krishnan R
manufacturer - Bangalore, India


2007

A. Check your trivalent status in chrome bath that should be less than 6 gm./ltr. Second increase the no. of microcracks on the job more than 400 cracks/linear cm.

Kuldeep Singh
- Pantnagr , Uttrakhand (INDIA)



"Hard Chromium Plating"
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"Chromium Plating"
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July 19, 2013

Q. Can we achieve 500 Hours Salt spray test on Duplex nickel hard chrome plated steel part?

Chandra Prakash
- Noida, India


September 2, 2013

Q. Can we achieve 500 hours salt spray test on ms seamless pipe having OD 219 mm, Length 1070 mm by duplex nickel hard chrome plating?
How much coating thickness is needed for this test.

Chandra Prakash [returning]
- Noida, India


September 2013

A. Hi Chandra. I think it's borderline possible -- but carefully re-engineering a plating process to attempt to pass a wrong and non-informative accelerated corrosion test doesn't seem like a very productive path to follow :-)

The thing is, real-world corrosion is a complex phenomena and we think that, for the case of nickel-chrome plating, the standard ASTM B117 [link by ed. to spec at TechStreet] salt spray test is rather non-informative because it poorly imitates real-life. CASS and Corrodkote tests seem to more accurately predict the life of nickel-chrome coatings.

I think what you might want to do is decide what life you need under what real-world conditions, and then try to design an accelerated corrosion test that will be helpful towards predicting whether the parts will pass the real-world needs. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


September 6, 2013

A. ASTM B456 [link by ed. to spec at TechStreet] has the specification for nickel/chrome plating corrosion resistance. It lists the thickness needed and how many hours the plating will survive various tests.

jim treglio portrait
Jim Treglio
PVD Consultant - San Diego, California


September 7, 2013

Q. My question is simple what process to be adopted by us to achieve 500 hours salt spray test (CASS) on ms seamless pipe having OD 219 mm, Length 1070 mm by duplex nickel hard chrome plating?
How much coating thickness is needed for this test.

Anyone help my ?

Chandra Prakash [returning]
- Noida U.P. India


October 17, 2013

A. Hard chrome is a poor corrosion protector. It only gives approx. 48 hours in NSST.

sara michaeli
sara michaeli signature 
Sara Michaeli
chemical process supplier
Tel-Aviv, Israel



October 22, 2013

A. Hi Chandra,

500 hours of a CASS is quite a challenge for any coating! I guess if it was me I'd go with about 75 microns of nickel undercoat followed by chrome to the finish size, but would probably want somewhere around 100-150 microns as a minimum.

I'm not going to guarantee that it will work, but it is a starting point.

Brian Terry
aerospace - Yeovil, Somerset, United Kingdom


October 23, 2013

A. Hi,

The only way to receive 500 hours in a salt spray test for chromium is to pulse plate the chrome.

Regards

anders sundman
Anders Sundman
3rd Generation in Plating
Consultant - Arvika, Sweden




Need Nickel-chrome plating to survive 500 hour CASS test

May 8, 2014

Q. My question is simple what process to be adopted by us to achieve 500 hours salt spray test (CASS) on ms seamless pipe having OD 219 mm, Length 1070 mm by duplex nickel hard chrome plating?
How much coating thickness is needed for this test.

Anyone help me?

Chandra Prakash [returning]
- Noida, U.P. INDIA


May 2014

thumbsdownHi Chandra. This is the 4th time you've asked your "simple" question on this page, and it was also asked asked & answered a 5th time on letter 54204.

Please try to PARTICIPATE in the discussion, phrasing your on-going questions in terms of the many answers that have already been offered to you, so we can keep moving forward. But rather than thanking any of the six people who helped you for their efforts on your behalf and engaging them, you simply ignore them and keep posting the same question again & again, insisting that it is "simple" :-(

It may have worn out their patience ... it wore out mine :-)

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


May 10, 2014

A. Dear Sir,

500 hrs of CASS life for nickel plated MS pipe seems very difficult to achieve. Kindly favor with end application details. This can help us in understanding the need for such high performance from the coating.

Even for automotive tubular components such as Two wheeler handles, which are exposed to most severe (Grade 4) of outdoor atmospheric conditions under high intensity motion such high CASS life is not specified. It may be Neutral Salt spray test life. Please Confirm.

Regards,

Dilip Thakur
- Mumbai India



December 2, 2015

Q. We require hard chrome plating with 10 to 15 microns to be withstand min. 76 hrs salt spray test coated on MS plate, as we have tried the test result is 46 hours only, then red rust is appeared. Please suggest alternate process but finish and wear resistance should be equal to hard chrome. Already we have tried Zinc-nickel coating, found satisfied on salt spray test -- but our client needs only hard chrome finish. Anyone can suggest please?

P gunasekaran
- Coimbatore, Tamil Nadu, India


December 2015

A. Hi. I am not familiar with the pulse plating which Anders describes, but you could ask him for more info.

Have you considered nickel plating under the hard chrome?

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E.
finishing.com
Pine Beach, New Jersey
Striving to live "Aloha"


December 4, 2015

A. Hi, I would not expect any real corrosion resistance from hard chrome plating to that thickness. Hard chrome is micro-cracked, due to the stresses in the coating, this means the base material can be attacked with relatively thin coatings of chrome. You either need to look at different technologies (e.g. thin dense chrome, which is not micro-cracked) or you need an undercoat as Ted has suggested (nickel or copper will serve your purposes, although nickel is the usual standard)

Brian Terry
Aerospace - Yeovil, Somerset, UK


December 7, 2015

A. Hi,
A combination with electroless nickel and hard chrome will give you more than 75 hour in salt spray test. But is a little difficult to activate the EN; to do the activation must be in an acid which contains sulphuric acid and hydrofluoric acid. The detail must be cathodic in activation.

Best regards

anders sundman
Anders Sundman, 4th Generation Surface Engineering
    Sundman & Nylander AB
Arvika, Sweden



December 10, 2015

Hi,
If anyone who plates hard chrome is interested about pulse plating with hard chrome, I can help you serious about it. We tested the plating in a salt chamber, after 500 hours no corrosion. So I know pulse plating works great.

Regards,

anders sundman
Anders Sundman, 4th Generation Surface Engineering
    Sundman & Nylander AB
Arvika, Sweden

email:



May 2, 2017

Q. Hi,
We are hard chrome plating on machined 270 mm OD ERW tubes, the issue rises when we get pin holes and minor cracks in the raw material as it gets rusted in salt spray chamber at 30 to 35 hours. Is there any particular standard describing the salt spray spec for hard chrome plating? What shall I do when we find pin holes in which hard chrome plating doesn't deposit? Kindly help me with this situation.

Ragavendra Sethuramalingam
Automobile service equipment's manufacturing - Coimbatore, Tamil Nadu, India



Hard Chrome Plating vs. Electroless Nickel

November 5, 2018

Q. Sir I want to do a complete technical comparison between electroless nickel plating and hard chrome plating for 1018 steel having plating thickness 30 to 35 microns in both cases. I want information like wear resistance, salt spray comparison, hardness, strength, life, etc.
I want complete specification and technical information in numeric form, not general statements.

Please do the needful.

Rahul Gulalkari
Bajaj Steel Ind Ltd, Nagpur - NAGPUR, MAHARASHTRA, INDIA


November 2018

A. Hi Rahul. I'm not aware offhand of any research paper which addresses that comparison, although some papers have been written about attempts to replace hard chrome with electroless nickel in specific applications. You can look for papers with the data and numbers you want at surfacequery.com, or possibly scholar.google.com.

As you probably know, parameters like salt spray hours cannot be used to predict the relative corrosion resistance of different finishes; and the wear resistance of an oil-retaining micro-cracked chrome plated hydraulic component is very different than the wear resistance of non-porous surfaces whether oiled or dry. Electroless nickel is available as nickel-boron, or low-, mid-, or high-phosphorous, heat treated or not (heat treatment increases hardness as the cost of reduced corrosion resistance). Electroless nickel composites can contain TFE, diamond dust, or other particles.

We've posted your inquiry hoping that another reader can point you to comparison papers. If no one refers you to them, you might look at https://www.finishing.com/consultants or the Indian Association of Metal Finishers Association of India to retain a consultant to help with the assignment. But I do feel obligated to offer the general warning that we can usually help you choose a finish for a specific application, but trying to generate charts which will tell you the best finish for arbitrary applications tends to be a fool's errand. Good luck.

Regards,

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



February 6, 2019

Q. Thanks to all previous responders. The information above has been quite helpful, especially the reference to ASTM B456 [link by ed. to spec at TechStreet].

For a steel base with 1000+MPa tensile strength, would baking (to prevent hydrogen embrittlement per ASTM B850-98 [link by ed. to spec at TechStreet]) need to be done after each plating process?

Secondly, when would one choose the Nickel plus Chrome coating on Steel versus Copper Plus Nickel Plus Chromium Coating on Steel? What are the benefits or disadvantages of one over the other?

Thanks,
Brian.

Brian Bernal
- Toronto, Ontario, Canada


February 2019

A. Hi Brian. Although the ASTM B456 reference caught you eye, your questions seem to be about hydrogen embrittlement and decorative nickel-chrome plating rather than hard chrome. I mention this because we have dozens of threads on your subject if you search the site with appropriate search terms.

I am not familiar with baking in between layers of copper-nickel-chrome plating, but baking before and after plating is common. You might need to check whether baking is sufficient though. There are grades of steel for which plating is unacceptable, and chrome plating is exceptionally prone to causing hydrogen embrittlement. General specs you might review include ASTM B849-02 [link by ed. to spec at TechStreet] and ASTM B850-98 [link by ed. to spec at TechStreet]

Copper plating before the nickel plating is not the usual practice when plating on steel these days; thread 0713 is about that exact subject. Good luck.

Regards,

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


February 16, 2019

Q. Thanks, Ted.

To clarify, my question or application is not decorative but entirely for protection. The plating will be for on an alloy steel piston rod in a hydraulic cylinder, to be used in marine environments. Our current design with no marine environment requirement uses chrome plating solely, with a bake afterwards. We expect it will corrode after some time.

We would like to use the sublayer of nickel for corrosion protection, while maintaining the wear and lubrication capability of the micro-porous chrome that we already have for the hydraulic seals that we know and trust.

The preceding input, as well as some direct inquiries with platers, have been very helpful in giving us an idea of what the spec and process might be.

Future feedback is always welcome.

Thanks,
Brian.

Brian Bernal [returning]
- Toronto, Ontario, Canada


February 2019

A. Hi Brian. A number of years ago there was serious interest in trying to replace the chrome plating on hydraulic cylinders with electroless nickel plating because of its far greater corrosion resistance. As you doubtless appreciate, the efforts weren't very successful because smooth electroless nickel is no substitute for the porous oil-holding nature of hard chrome plating. But I believe it did result in quite a bit of research into electroless nickel followed by hard chrome. This would seem to me to be the right approach for a marine environment. Please try surfacequery.com and scholar.google.com and see what you can find (maybe with the search term "rod AND electroless AND nickel AND hard AND chromium"). 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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