[TowerTalk] Chrome moly/end caps

[Bill Coleman AA4LR]

On 10/13/97 9:00, CQK8DO@aol.com at CQK8DO@aol.com wrote:

>In a message dated 97-10-10 21:36:01 EDT, you write:
>
><< Do not weld on 4130 in the high temper states ie yield strength over
> 100,000 PSI. The weld arc will locally destroy the high yeild strength
> you paid for and provide a discontinuity that provides a site for cracks
> to start.
>  >>
>
>Just got to reading the mail... I have to take issue with this as welding
>4130 is how we build aircraft fuselages, race car frames, etc....

But, typically, we don't use high-strength temper treated 4130. That's 
what he's discussing.

> After
>welding is finished the steel is re-tempered in the area of the weld by a
>process called normalizing...

This is done to releave the internal stresses that might have formed in 
the process of cooling after each weld was done. It is not the same has a 
high-strength tempering that is done on the ENTIRE mast.

And, ironically, Piper aircraft build a large number of 4130-framed 
airplanes, and used TIG welding WITHOUT normalizing. There has yet to be 
evidence of a manufacture-induced weld-stress fracture. Something to say 
for quality jigging and professional welding....




Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr@radio.org
Quote: "Not within a thousand years will man ever fly!"
            -- Wilbur Wright, 1901


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