Mark,
You are correct that use of vacuum heat treat will reduce the scale. If you
plan on heat treating in a final condition that scale produced by the
carburising furnace contains micro cracks and other surface contamination
that would be detrimental to the material properties. On use carburising on
the chrome steels if you are planning to machine to finish size after the
heat treatment.
In my aerospace world we only use vacuum...but I believe the material spec
doesn't require it (except for titanium).
aaron
-----Original Message-----
Sent: Friday, July 16, 2004 05:21
To: fot@autox.team.net
Subject: Re: Axle Steel
Aaron, I do not agree. Vacuum heat treat will reduce surface scale but is
very expensive. Machining after heat treat removes that issue. We heat treat
4130/4340 for aerospace everyday, never vacuum.
Mark
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