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Re: [TowerTalk] 4130 Chrome-Moly Grades

To: "Ron Hylton" <>, <>
Subject: Re: [TowerTalk] 4130 Chrome-Moly Grades
Date: Thu, 13 Jul 2006 13:29:25 +0000
List-post: <>
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 heat 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 

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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