BigAl1

Hi All,
Has anybody experienced Hydrogen Embrittlement problems for any hardware they had plated Yellow Zinc Dichromate? I'm about to get all the underside hardware done, and as much of the engine hardware I can get into the order. The plater came back with a question about H.E.R. (Hydrogen Embrittlement Relief), and me not being sure what to do, I'm asking here. Should I be concerned? I saw Greg B had a pile of hardware plated during the rebuild for his son, so hopefully he chimes in here.

Thanks

Larry Velk

The way it used to be done for chrome is a simple heat soak - of course the temp and time was supposed to be controlled. If the plater is asking "do you want it done?", I'd say 'sure', as it wouldn't be expensive. The method used to plate the yellow cadmium fakee-do doesn't seem severe enough to require treatment, but the usual rule is listen to the experts if you chose the expert properly.
BTW, in "Prepare to Win" by Carrol Smith he mentions the bake must be right after the plating, so there is some technique to the method. Nickle also must be baked, but I'm still not sure about the more modern 'green' plating.

Chris

Never been asked that question, just dropped it of and picked it up

I did find out not all platers are equal, the local guys could not plate some brake calipers for another car, looked like crap. Some guys out in Utah got it done perfectly.

Rob Edwards

Greg's had a couple of batches done for me and I never heard any discussion about it. If there's anyone that would be worried about metallurgical fatigue or the plating process possibly causing a mechanical failure, it'd be Greg. But maybe he specifies some mitigation when he drops hardware off, dunno.

Jim M.

IIRC there is a 4 hour window between the acid wash and the baking process. It's the baking that removes the hydrogen thereby eliminating the possibility of hydrogen embrittlement. As stated above your answer should be "sure" again it won't cost much.

worf928

Yellow-chromated Zinc electro-plating I'm familiar with. Dunno if that's the same as Yellow Zinc dichromate.

dr bob

There's been some casual discussion with a local plater in sunny Burbank, who still does the real yellow cad rather than the zinc-plus-yellow chromate. I heard it from an owner who had some plating done by them. Passed the info to Rob for Greg, Rob told Dwayne, Dwayne has been in touch with them. Batch size is 150#, so it will take a couple big buckets of bolts and washers to make the effort most economical I guess.

Best schedule I have is going to be maybe 5# of stuff next spring when the timing belt gets changed and the top gets refreshed. I'd love to do all the suspension bolts, trim bolts in the wheelwells, through bolts in the calipers, etc. But I'm not quite ready to disassemble the car completely just to get the plating brightened. I still drive the thing!

WallyP

Wow! I would have bet money that no one in Cali still did real cad plating!

dr bob

I was thinking that too. The residue and wash water has to be treated almost like radioactive waste. But we have a niche group of aircraft parts manufacturers around here, so maybe they still spec the real thing for those particular markets. Getting a good even cad finish makes a part more yellow than the blooming red-streaked-gold that seems to be th e commn end product of the chromate over zinc that most places do these days. Plus the cad plating easily outlasts the zinc in service, much less reactive. If it wasn't for needing those pesky liver and brain cells...

GregBBRD

Hardware, at the alloy ranges that are used for our car's construction, doesn't really suffer from hydrogen embrittlent, as much as higher grades of hardware. Corrosion, at the root of the threads, is a much more powerful problem. That being said, it certainly doesn't hurt to let them treat it. Of course, you'll never really know if they really do it!

gb

beentherebaby

Minimum three hour bake @ 375 F, within four hours of plating. Cheap and good practice.

http://www.finishing.com/145/37.shtml

BigAl1

Thanks for all the info. I'll go ahead with requesting the H.E.R..