4130 can't be OA welded?

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 .
Best To All
Phil Lohiser
"Stuart & Kathryn Fields" wrote in message
.. .
Phil: The stress relieving that you described: of slowly raising the
temperature to1020 Deg. F and holding it for 3hrs then dropping at a
certain rate is certainly different than heating to cherry with an OA in
less than a minute and then letting it cool in less than a couple of
minutes. The guy I referenced in an earlier posting was responsible for
the TIG welding of 1800 Aerostar engine mounts that did not crack and had
no post weld heat treatment. That, while anecdotal and not a report of a
truly scientific examination of the weld joints using metallurgical
techniques, does carry some weight with me. Not to mention his survey of
a group of airframe manufacturers which included Piper and Mooney that
were surprisingly, using MIG with no pre or post heating. An awful lot of
successful experience of welded joints without OA "Stress Relieving".
BTW my Baby Belle gets trailered to a bunch of events every year and has
in excess of 125,000 trailer miles over roads that have set ELTs off and I
have never found a crack in any of the welded joints and this includes a
17' tail boom that has a bunch of welded cluster joints and is not
supported anywhere but at the front end by 4-5/16 bolts in double shear.
My ship is one of at least 5 with high trailer miles and I've yet to hear
of a cracked weld joint. This is an accumulation of about 15years
experience with these ships.
I note however that these joints were designed with amateur builders in
mind and the frame and joints are not designed close to the ragged edge
but have a sufficient margin to allow for less than expert welders. E.g.
the tail boom is of 0.049 wall tubing where similar tubing on the Bell 47
is as small as 0.025. There are a lot of contributing factors to a
successful TIG welded joint.
I know of no metallurgical research or experiments that prove the very
quick and uncontrolled OA "Stress Relieving" is an effective useful tool
in producing a successful TIG welded joint. In fact my limited research
into the metallurgical reports found reports of decreased tensile strength
in the material as the result of Post Weld Heat Treatment. I know that
this is an area of strong opinions and I'm sure that I will be digging
into the metallurgy of welded joint more as I feel like I've just barely
got my nose into an area that is much more complex than I thought.

Stu
"Phil" wrote in message
...
NASA published an advisory many years ago that was reprinted in Sport
Aviation , I don't have the article at my fingertips , as I remember ,
NASA stated that any 4130 weld assembly that was TIG welded and used on
Aircraft should be post heated via Oxy/Acet , anyone who has ever done
any welding and especially ARC welding must know and has experienced the
tension that has built up after the weld has cooled , just a pinch of
common sense would tell you that this tension load will be there for the
life of the weldment , to raise the temp. of a given cluster up to a
point that allows that cluster to seek it's sweet spot without that
locked in tension and possible premature failure would only make common
sense , NASA is far from perfect but they were on the money with this
advisory .
I don't know how many people that write books on welding have actually
worked on the floor with real airplanes and have actually welded on
commercial airplanes , I have seen many lineal inches of Oxy/Acet weld
laid down and never saw a crack or fracture of that weld that occurred on
the floor even before an assembly was painted , I have seen many TIG
welded assemblies that would crack shortly after welding and again before
they saw paint , if you have an engine mount that needs a small amount of
machining and the machinist is damaging high speed steel end mills with
hardened 4130 , this has to be very telling , it's been a few years since
I worked for a Jet engine repair station , as I recall , all welded parts
were placed in a oven and slowly raised to about 1020 Deg. F. and held at
that temp. for 3 hrs. and then the temp. was dropped at a certain rate
for several hours , they didn't do this for there own pleasure , this was
FAA mandated .
Best
Phil Lohiser
"wright1902glider" wrote in message
...
While browsing a bit more of that "good 'ole internet wizdom", I ran
accross this page:

http://www.ihpva.org/com/PracticalIn...materials.html

Its a human-powered vehicle website, but on this page, the author
seems to think that 4130 cro-mo steel can't be welded with an oxy-
acetylene torch. Does this sound right? It was always my belief that
we've been OA welding airplanes out of the stuff for decades. Who is
wrong on this point?

Harry "I'm still stuck in the wood-age" Frey

On Tue, 1 Jan 2008 09:28:01 -0800, "Stuart & Kathryn Fields"
wrote:

Morgans: According to everything I read in my research for the article I
wrote, the "Quick stress relieving" by the few seconds of OA after a TIG
weld do not effectively relieve the stress and can actually cause a
weakening of the weld joint. There appears to be quite a bit of truly
scientific experimentation to support this view. As a retired engineer, I'm
more prone to accept the scientists report over the anecdotal evidence from
more questionable sources. All that said, I can relate to failures that I
saw as the result of a crash of Chrome Moly airframe. Tube failures near a
cluster showed a separation that occurred just a short distance (1/4") from
the weld that was relatively clean and very even and roughly resembling a
fatigue failure zone. The Richard Finch that I referred to in an earlier
post wrote the book called Performance Welding and cited his experience at
Aerostar. I'm going with him and his belief supported by the research I did
and will not allow an OA torch near my TIG welded joints.
BTW, with the exception of some welds on my SS exhaust, none of my TIG welds
which includes fuel and oil tanks and the SS railing on a 35' Sailboat have
shown any cracking. None of these had OA "Stress Relief".

Stu
"Morgans" wrote in message
news

"Stuart & Kathryn Fields" wrote

Thanks Rich: That coroborates all the stuf I found thru digging thru
University research papers, certified welding instructors, Metalurgical
studies and a bunch of writings of people like you and the EAA tech
counselor. All that said, I have an IA friend that still insists on the
OA " normalizing" or "stress relieving" after a TIG weld. However, not
on my helicopter.

So, do you think that the tig welding does not induce the stresses, and
therefore not need the quick OA "stress relieving" or what? I'm
interested in the reasons you came to this conclusion.

I may need to make cromolly engine mount, but the rest of my dreambuilt
airplane will not require any normalizing.

I hear wood airplanes do very poorly with an OA torch held at their
"clusters." ;-)
--
Jim in NC


The commonly accepted knowlege on this subject is to use a low alloy
filler rod when tig-ing 4130, in still air, and no post-heat stress
relief.
The low alloy filler draws some alloy from the base metal (tubing) and
the fillet is thicker than the substrate, so the total strength of the
"low strength" weld is equal to or superior to the base metal. The
base metal is "drawn" - it is less hard, and slightly weaker but less
prone to cracking, so you get a good, solid, reliable joint.
Cracking is extremely rare when the structure is built this way.

--
Posted via a free Usenet account from http://www.teranews.com

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

clare at snyder.on.ca wrote

The low alloy filler draws some alloy from the base metal (tubing) and
the fillet is thicker than the substrate, so the total strength of the
"low strength" weld is equal to or superior to the base metal. The
base metal is "drawn" - it is less hard, and slightly weaker but less
prone to cracking, so you get a good, solid, reliable joint.
Cracking is extremely rare when the structure is built this way.

Thanks for that explanation. The bit about the drawing makes good sense.

Damns, now I gotta go out and find a tig welder and start practicing! g
--
Jim in NC

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

On Jan 1, 9:57*pm, wrote:
On Jan 1, 4:32 pm, "Phil" wrote:


* * * * * Steels aren't hardenable under .40% carbon. 4130 is .30%.

* * * * * Dan

.
I don't think this is quite true. The data from AR-MMPDS-03 for 4130
and 4135 says the following. It plainly gives the tensile strengths
and other data for 4130 and 4135 heat treated to several different
levels of strength, compared to normalized (no heat treat). This is
the guiding technical standard that all metals in the Space Shuttle,
Space Station, and many other high tech NASA projects are governed
by.
4130 is heat treatable to 180 ksi and 4135 to 200 ksi. The un-
heat treated strength is 75 to 90 ksi. It is true that higher carbon
content (to a point) allows for higher treat heat levels, as the
higher level for 4135 vs 4130 shows.

Regards,
Bud

Several years ago a EAA member was building a four place experimental with
4130 as the airframe , the gentleman either couldn't or wouldn't learn to do
GAS welding and he ask the FAA if he could braze the structure together ,
FAA said that as it was under the experimental category and they could not
prevent him from brazing his four place bird together but they would like
him to make some samples to proof test his idea , samples proved his concept
and FAA gave him a green light , I think the filler rod was Eutectic FC16 ,
I did get a couple samples of the filler and made my own samples of 5/8 X
..035 4130 , tubing bent and finally broke after great load was applied , no
failure in the filler , only adjacent to it , the problem with this material
is that it uses a Flux coating and some of it is going to get inside the
tube and the stuff will corrode.
Phil
wrote in message
...
On Dec 28, 2:57 pm, wright1902glider wrote:
the author
seems to think that 4130 cro-mo steel can't be welded with an oxy-
acetylene torch.
--------------------------------------------------------------------------------

Pure bull****. Indeed, for the stresses encountered in bicycles
(which is what he's talking about) there are any number of BRAZING
compounds that yield joints stronger than than normalized 4130.

O/A does just fine airframes... and for bike frames.

"Richard Riley" wrote in message ...
On Fri, 28 Dec 2007 19:46:57 -0800 (PST), "
wrote:

On Dec 28, 2:57 pm, wright1902glider wrote:
the author
seems to think that 4130 cro-mo steel can't be welded with an oxy-
acetylene torch.
--------------------------------------------------------------------------------

Pure bull****. Indeed, for the stresses encountered in bicycles
(which is what he's talking about) there are any number of BRAZING
compounds that yield joints stronger than than normalized 4130.

O/A does just fine airframes... and for bike frames.

If brazing gives stronger joints that normalized 4130, why aren't we
brazing airframes?

(I'm not saying it's an incorrect statement - I know better than to
disagree with VD on something like this. I just figure there must be
a reason, like the brazing compounds are more expensive.)


Won't withstand high temperatures?

On Jan 1, 9:54 pm, Richard Riley wrote:


If brazing gives stronger joints that normalized 4130, why aren't we
brazing airframes?

(I'm not saying it's an incorrect statement - I know better than to
disagree with VD on something like this. I just figure there must be
a reason, like the brazing compounds are more expensive.)
-----------------------------------------------------------------------------

Dear Richard,

That's a good question but you're asking the wrong guy.

Also, it isn't just ANY brazing, it is a form of eutectic brazing
developed specifically for alloy steels, initially for use in military
weapon systems as a means of reducing the cost & weight of certain
structures. The components are cut very accurately on CNC equipment
and most of the joins were done in an oven with the parts secured in a
jig.

The only problem I can see with this method is that REPAIRS would be
rather difficult; certainly not as convenient as with an O/A torch and
wire coat hanger :-)

Dig through French's books. If he hasn't written something about it,
he should have.

-R.S.Hoover

On Jan 1, 11:37 pm, wrote:
On Jan 1, 9:57 pm, wrote:

On Jan 1, 4:32 pm, "Phil" wrote:

Steels aren't hardenable under .40% carbon. 4130 is .30%.

Dan
.

I don't think this is quite true. The data from AR-MMPDS-03 for 4130
and 4135 says the following. It plainly gives the tensile strengths
and other data for 4130 and 4135 heat treated to several different
levels of strength, compared to normalized (no heat treat). This is
the guiding technical standard that all metals in the Space Shuttle,
Space Station, and many other high tech NASA projects are governed
by.
4130 is heat treatable to 180 ksi and 4135 to 200 ksi. The un-
heat treated strength is 75 to 90 ksi. It is true that higher carbon
content (to a point) allows for higher treat heat levels, as the
higher level for 4135 vs 4130 shows.

Regards,
Bud

Didn't say it wasn't heat-treatable. Said it wasn't hardenable.
Hardness is usually linked to crack tendencies. Tensile strength can
be changed with heat-treat, I know, but cracking on aircraft tube
structures, as I understand it, is more due to the cooling and
shrinking of the local area and consequent rise of tension in that
area.

Dan