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Guest wkong

Due To Problems With Hydrogen Embrittlement In Zinc Electro-plated Bolts.

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Guest wkong

Due to problems with Hydrogen Embrittlement in Zinc Electro-Plated bolts.

would anyone know the exact differences in the coating processes and how the Dacromet

coating (dipped in solution and baked at 300 degrees centigrade) affects the material properties so? :P :specool:

 

 

Dacromet--trademarked by Metal Coatings International.

 

Purpose&Scope,

Have anyone can help me to abate the Hydrogen embrittlement?

 

Now we want to do a zinc electrodeposition coating, the details as following:

 

Raw-Materil:

Chinese grade 42CrMo steel (requirement, Current we used).

Japanese grade SC440M.

AISI 8115 steel.

 

Chemical Composition:

Carbon .38 to .43%

Manganese .75 to 1.00%

Phosphoures .035% maximum

Sulphur .040% maximum

Chromium .80 to 1.10%

Molybdenum .15 to .25%

Silicon .15 to .35%

 

Mechanical Properties

Tensile Strength 95 KSI min.

Yield Strength 60.5 KSI min.

Elongation 12% min

Hardness Rockwell C 38-35.

 

Heat Treatment

1.The steel will be quench and tempered to Rc28-35(mid-radius),

2. Machining surfaces to achieve final size(15Ra).

 

Coating process: ( Per customer Requirements)

Please see the attachments>>> Specification.jpg

 

Question:

 

1.Our parts was rejected due to the hydrogen embrittlement! Haveanyone

have the better way to abate the hydrogen embrittlement?

2. what the reason effect the hydrogne embrittlement? Hardness? Carbon content? surface finish? ....

3.Have anyone know how to check the lacuna?

4.Forthermore have anyone know the DACROMET technology?

 

Thanks in advance !

Best Regards!

 

Roger.Kong

post-14019-1227084858.jpg

post-14019-1227084868.jpg

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Guest newt @ MWE

hey

 

Its fairly difficult to understand what you are asking for because of the translation, but I can try.

 

Question: Is the issue with the current plating process? or the quality of the application?

Is the issue with the constructed material itself?

and finally, are these for Boeing?

Never heard of Dacromet.

 

If the current plating process is the issue, find a less brittle plating.

If the quality of the application is poor, get someone else to plate it right (more expensive?)

If the current construction material is too brittle, change the material or the design to compensate.

If these parts are failing, you may have to accept the fact that they were poorly designed and should be scrapped and re-designed.

 

Don't mean to sound snooty, just seems like a simple solution to me.

 

newt

 

ps - are these for Boeing?

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Guest wkong

Newt,

Thanks

 

Due to problems with Hydrogen Embrittlement in Zinc Electro-Plated bolts.

would anyone know the exact differences in the coating processes and how the Dacromet

coating (dipped in solution and baked at 300 degrees centigrade) affects the material properties so?

 

 

Dacromet--trademarked by Metal Coatings International.

 

 

These for Auto and Boeing

 

Best regards!

 

Roger.

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Guest superbad

You'd be better off asking your plating supplier rather than a bunch of art college graduates on an internet forum.

 

Hydrogen embrittlement is caused primarily by hydrolysis during the electroplating process. You can bake most of that hydrogen out after plating, but I highly doubt your factory is well-run enough to do it correctly. It has to be done very quickly after plating. Dacromet looks like it will work too, if it passes your other requirements. But really, you should be asking the Dacromet people, not us.

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Guest wkong
You'd be better off asking your plating supplier rather than a bunch of art college graduates on an internet forum.

 

Hydrogen embrittlement is caused primarily by hydrolysis during the electroplating process. You can bake most of that hydrogen out after plating, but I highly doubt your factory is well-run enough to do it correctly. It has to be done very quickly after plating. Dacromet looks like it will work too, if it passes your other requirements. But really, you should be asking the Dacromet people, not us.

 

 

Thank you for you kindly advice, we try to improve the process of Dacromet !

Also we try to do the testing of JS500.

 

Thanks and best regards!

 

roger

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