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...--
Scott, kb0fhp, writes:
<<..For a Steel to be susceptible to Hydrogen Embrittlement, there are
several
things that must occur at the same time: First you have to have a
susceptible material; second, you have to have hydrogen present dissolved in
the metal; and lastly, you need a low strain rate. Static tensile loads are
appropriate.
In general, the all steels are susceptible. Cr-Mo steels, i.e., 4140 and
Cr-Ni-Mo (4340) are some of the most susceptible - if they are heat treated
to a tensile strength level above 200KSI. This means, in general, heat
treated to above Rockwell C 43. Practically all steels are susceptible
above HRC 43. The tower materials used are typically cold rolled, annealed
and pickled, or hot rolled, then galvanized AISI 1018 steel. The hardness
of this material is on the order of HRC 25 - not susceptible. The Cr-Mo
masts most people use today are also cold rolled and annealed AISI 4140 or
4340 at approximately 135 ksi (HRC 28) - again not susceptible....SNIP...>>
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