"Grant Erwin" wrote in message
...
A long time ago when I was a teenager first starting work in Seattle's
shipyards, an old machinist who rode Harleys told me that whenever he
got a part chromed he put it in his oven for some period of time to
keep it from getting brittle. I figure maybe he was talking about
hydrogen embrittlement, which could indeed happen in the acid chroming
bath.

I figure heating the metal would expand the lattice, allowing the (tiny)
hydrogen atoms to migrate. Presumably at least half of the ones right
near the edge would migrate right out of the part, and the remainder
would diffuse throughout the part, lowering the risk of a crack starting.

Is this what actually happens? If I soak some parts in salt/vinegar (a
real good way to remove rust from small parts) but am worried about
H embrittlement, can I bake the parts at say 350F for a couple of hours
and solve the problem?

Grant Erwin

Grant,

In the salt/vinegar solution, there probably isn't enough hydrogen ions to
embrittle your parts. The embitterment effect gets worse the harder the
part is on the Rockwell scale. In the A/C finishing business, we had to
bake some of the exotics used in high stress applications for 23 hours @ 375
degrees to relieve embitterment, record the bake cycle and attach it to the
certs.

Ed Angell