Metal finishing Q&As since 1989
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AMS2416 nickel-cadmium effect on alloy steels
Q. Can anyone provide data or a reference to data concerning the effect of diffused nickel-cadmium plating on the fatigue performance of steel components (specific info. on fasteners would be best). Is it considered better or worse than cadmium in this respect?
John Ullman1999
A. The FAA did an excellent document on liquid metal embrittlement of high tensile, high speed components. Have a look at their web page under technical info.
Dave Brackenridgeaerospace plating - Germiston, South Africa
1999
Q. What is the difference between cad plating and nickel cad?
Mahdi Abdollahi- Tehran, Iran
August 19, 2009
A. Hi, Mahdi. They are different materials designed for different applications, but nickel-cadmium diffused coatings will withstand higher temperatures than plain cadmium.
What is your application that motivates your question? With that info we may be able to help you. Without it all we can do is refer you to some "must-have" plating books where you will find the properties, uses, and application methods for different platable metals and alloys including cadmium plating and nickel-cadmium diffused coatings. Good luck!
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
August 18, 2009
Q. Does diffused nickel-cadmium plating in accordance with AMS2416 cause hydrogen embrittlement on high strength alloy steels, or have any deleterious effect?
Joe Mercurio- Orlando, Florida
A. Hi, Joe. Both nickel plating and cad plating cause hydrogen embrittlement. So do cathodic cleaning and acid treatments that may be part of the pretreatment protocol. But the baking for diffusion, if done immediately, probably solves the problem.
As to other deleterious effects on the steel, you should look up cadmium embrittlement and see if it's applicable to your situation. NASA warns, in their publication 1228, "Fastener Design Manual", that:
This process was developed by the aerospace companies for a higher temperature cadmium coating. A 0.0004 in. thick nickel coating is plated on the substrate, followed by a 0.0002 in. thick cadmium plate (per AMS2416). The part is then baked for 1 hour at 645 °F. The resulting coating can withstand 1000 °F. However, the nickel plate must completely cover the part at all times to avoid cadmium damage to the part. This process is expensive and requires close control.
Good luck.
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
A. Joe, the diffusion treatment of 630 °F for at least 30 minutes (per paragraph 3.2.4 of AMS2416) will serve as an extensive bake, so the traditional hydrogen embrittlement concerns of electroplating are relieved. I would second Ted's suggestion that you investigate any other possibilities for embrittlement- such as contact with titanium.
Lee Gearhart
metallurgist - E. Aurora, New York
Does diffused nickel-cadmium plating in accordance with AMS2416 cause a reduction in hardness/tensile strength on hardened alloy steels?
Joe FinneganProduct Engineer - Chicago, Illinois
2004
Hi, Joe. If proper baking for hydrogen embrittlement relief is not done, any plating can catastrophically weaken hardened steel alloys; but the baking must be done below temperatures where affect the heat treatment and strength of the part. Further, any plating can reduce the fatigue strength of a component because cracks in the plating can act as stress risers.
Speaking specifically of nickel-cadmium, that must be heated to at least 640 °F, I am not especially knowledgeable about metallurgy, but AMS2416 specifically cautions that it must only be used on alloys that are not weakened by that temperature.
Regards,
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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