Summary for de-embrittlement process Discussion
brittle after de-embrittlement process is the core issue here: Raymond Goh asked why a zinc-plated automotive part still has a tang that breaks during assembly after the de-embrittlement bake. The quickstart note explains that electroplating and the acid pre-treatments can introduce atomic hydrogen, which can embrittle hardened steel unless it is baked soon after processing. James Watts agreed with Ted Mooney’s warning that the part may not be the only problem: the design should be checked, and unplated parts should be tested to see whether they also fail. He suggested a pre-bake or shot peening if needed, and said that getting parts into the oven within 30 minutes and baking them for 4 hours at 375 °F should normally prevent trouble. He also pointed out that excessive time in the acid etch is another common cause of hydrogen-related brittleness.
Quickstart:
Electroplating, as well as the acid treatments before it, create atomic hydrogen which can penetrate and embrittle hardened steel parts, turning them to glass. If the components are hardened steel, as opposed to low carbon “soft” steel, they must be baked shortly after processing to release that hydrogen or the components may be permanently “embrittled”.
Q. I work in the automotive industry and having problem with part (zinc plated and gone thru the de-embrittlement process). During assembly of this part, the tang on the part is too brittle and breaks off during the assembly process. Please advise.
Raymond Goh
Quality Engineer – Melbourne, Australia
2007
“Solutions to Hydrogen Attack in Steels”
by P. F. Timmins (1997)
on Amazon or
or
(affil link)
Current Solutions to Hydrogen Problems in Steels
(includes 7 papers / 34 pages on electroplating)
on Amazon
or
(affil link)
A. Hydrogen embrittlement damage occurs quickly and is permanent, Raymond. You must do the baking almost immediately — how much time actually elapsed before baking?
Ted Mooney, P.E.
Striving to live Aloha
finishing.com – Pine Beach, New Jersey
Need quick confidential answers? $25
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A. What Ted said is extremely true.
Next, is the part properly designed? Try mounting a couple dozen unplated parts and see how many break.
Next, you may need to do a pre-bake or a shot peening process.
But normally, if the parts are in the oven within 30 minutes and spend 4 hours with the parts at 375 °F, you should have no problem. Spending too long in the acid etch is another common cause.
James Watts
– Navarre, Florida