Dan , take a piece of 4130 and heat it to dull red and quench , it will
definitely take heat treat , some of the older A/C had the entire fuselage
heated and quenched and tempered in order to develop a higher teasel
strength , on the order of 150 K as opposed to the normal 90-100 K for
normalized 4130 ,this process caused a real problem for repairs as the
average shop couldn't repeat the heat treatment process .
Best To You
Phil Lohiser
wrote in message
...
On Jan 1, 4:32 pm, "Phil" wrote:
Like I said in my first little post , religion , politics and I guess you
could add motor oil to the list of a million things that are debatable ,
I
will still stick with the NASA report and a little common sense , the
last
engine mount that I TIG welded was brought up to cherry red , both to do
a
little alignment adjusting and to help level out some of the built up
strain
from the initial TIG welding , my wife has a diamond ring that is very
hard
but not very ductile , I really don't like the idea of having an EAA
Biplane
engine mount turned into a diamond , not very flexible , even 1020 can
develop hardness after welding , raise the carbon to 30/100 of 1% and
things
really get hard , go to 4140 and you are headed back to the diamond ring
state again.

Steels aren't hardenable under .40% carbon. 4130 is .30%.
Got to be careful with the flame. Getting it too rich in
acetylene makes it a carburizing flame and will raise the carbon
content of the steel.

Dan