Where the
world gathers for metal finishing
Q&As since 1989


-----

Hydrogen embrittlement baking cycles

1999

We have been baking, for hydrogen embritllement, our cadmium and others plated deposits to a theory that on a bake cycle of 375 Deg for 4 hours, where you have to chromate after baking, that we can bake at 150 degs for 5 hours. Supposely there was a specification that stated to that. This specification is now not available or lost and can't find it.

what I would like to know if anybody has heard of this and better yet maybe some body might know where I might find it

thank you
chris

Chris Snyder
plater - Charlotte, North Carolina

---

I have never heard of that in Mil spec, AMS or several major aerospace companies.

140 is normally as hot as you want to go on a chromate. My personal opinion is that 150F for 5 hours is nearly worthless for hydrogen embrittlement relief. I somewhat doubt if 24 hours at that temp would do much.

James Watts
- Navarre, Florida
1999

---

I agree with Mr. Watts. Five hours at 150F (F assumed) will not buy much for hydrogen embrittlement relief. Diffusion rate is an exponential function, as I recall. Therefore, to achieve an equivalent result to that of 375F for 4 hours would take at least 20 hours if not more.

Larry Hanke
Minneapolis, Minnesota
1999