Forwarding this e-mail exchange, for the benefit of the group.
73,
Ron AD7L
----- Original Message -----
From: kb0fhp@comcast.net
To: Ron Hylton
Sent: Thursday, July 13, 2006 8:59 AM
Subject: Re: [TowerTalk] 4130 Chrome-Moly Grades
Standard metallurgist answer - it depends. While a non-heat treated grade of
4130 will not have the strength of heat treated 4130, it is substantially
stronger (double or more) than normal pipe and tubing made of AISI 1010
Cold-Rolled, as is normally found and readily available.
It is possible to obtain heat treated 4130 from steel warehouses and
distributers. It is also obtainable from aircraft parts suppliers - Wickes
Aircraft Supply comes to mind. Heat treating is relatively cheap....if you are
going to go to the lengths (excuse the pun) to obtain 4130 aircraft or airframe
grade tubing, then it is silly not to heat treat it. Otherwise the much less
expensive 4130 is more than adequate....
Personally I prefer 4340, heat treated to about HRC 40-45.
As always, know your material, its limitations, and design accordingly.
Scott
-------------- Original message --------------
From: "Ron Hylton" <ad7l@hevanet.com>
> Hi Scott,
>
> Thanks for your response. If I am reading your response correctly, are you
> saying that if I bought this tube, I would then have to arrange for heat
> treating, and that it is not ready to use "off the shelf" (of course it
> would need to be galvanized, too.)
>
> Thanks,
> Ron
>
> ----- Original Message -----
> From:
> To: "Ron Hylton" ;
> Sent: Thursday, July 13, 2006 6:29 AM
> Subject: Re: [TowerTalk] 4130 Chrome-Moly Grades
>
>
> > Depending on the specification: Condition N is normalized and ready to be
> heat treated. CDSR is stress-relieved. More than likely the material is in
> a form similar to hot rolled, and not normalized for uniform microstructure.
> It is heated to some nominal temperature to relieve any stresses from the
> manufacturing process. The final commercial grade is an unknow, but I would
> suspect that it is simply as-received from the mill. It would be in a
> microstructure similar to a hot rolled microstructure. However, all these
> grades can be heat treated to fairly high strength and toughness - and
would
> yield (excuse the pun) excellent results. Another big difference between
> the grades is the amount of testing done - the AMS grades require more
> testing, but the alloy chemistry is essentially the same. There may also be
> some difference in the inclusion content which would affect fatigue life
and
> impact strength.
> >
> > As a metallurgist, I would feel comfortable with using any of the grades,
> especially if they were he at treated appropriately. The best is probably
> the airframe grade, followed by the aircraft grade, and finally the
> commercial grade. For the purpose of mast materials, the service is
> relatively low, with failure usually being overload instead of fatigue. Any
> one of them would work....
> >
> > Hope that helps
> >
> > Scott, KB0FHP
> >
> > -------------- Original message --------------
> > From: "Ron Hylton"
> >
> > > Here in the Portland metro area, we have an excellent source of tubing
> from
> > > a company called Tube Service. They offer several grades of 4130 alloy
> > > Chrome-Moly tube, including:
> > >
> > > 4130 Airframe (Cond. N) Specs: Mil-T-6736, AMS 6360
> > > 4130 Aircraft (CDSR) Specs: AMS-6371
> > > 4130 Commercial Specs: ASTM A-519
> ; > >
> > > My question is, which grade is typically used for masts?
> > >
> > > 73,
> > > Ron AD7L
> > > Hillsboro, Oregon
> > >
> > >
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> > >
> > >
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>
>
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