Thank you, Scott. I'm adding your comments to a file I keep on metals
processing.
--...MARK_N1LO...--
Scott, kb0fhp, writes:
<<These alloys are susceptable to hydrogen embrittlement. But the black
oxide process (hot) involves the immersion in a series of caustic salts at
295F. Essentially, the caustic (NaOH) reacts with the iron surface creating
an adherant iron oxide (typically Fe3O4-magnetite). This reaction releases
hydrogen at the surface of the steel. However, there may be inhibitors or
other stuff in the hot bath that would not cause the formation of hydrogen -
similar to the low hydrogen form of cadmium plating. If you suspect
hydrogen embrittlement, the best thing to do is to do a hydrogen
embrittlement stress-relief for 24 hours at 325-375F.
>
>I tried looking up some information on stress-relief after black-oxide
>coating, but was not able to readily find it. I would ask your black-oxide
>supplier technical people. They love questions like that..... Scott >>
>
>-------------- Original message --------------
>
> > Thank you, Scott, for that excellent and learned summary of hydrogen
> > embrittlement!
> >
> > In my work, I make many custom tools, typically from AISI D2 and A2 tool
> > steels, at hardnesses typically from Rc45 to Rc55. However, I usually
>don't
> > have them plated (The Gov't tends to shy away from the toxic
>entanglements
> > of CAD plating) and few have weldments. At these hardnesses, steels tend
>to
> > be more brittle even without secondary effects.
> > I do frequently use black oxide coating (hot process). Will black
>oxiding
> > encourage the hydrogen embrittlement effect?
> >
> > Thanks,
> >
> > --...MARK_N1LO...--
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