4130 can't be OA welded?

Blueskies wrote:
"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?



Structural brazing works just fine - if done correctly.

But too much heat causes the brass to migrate into the grain
of the 4130 - resulting in cracks.

It HAS to be done right.
And there is no way to tell afterwards if it was or not -
until it breaks.


Richard

wrote:


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

4130 is indeed hardenable by heat treatment or cold working. And 4135
even more so. I have hardened them both using both water and oil
quenches, though if you took the time to read one of the metallurgical
tomes on the subject, you would find they are spec'd as an oil hardening
alloy. Water has worked fine for me on small sections, though my
default quench (i.e. the bucket next to the forge) is water with a layer
of olive oil floating on the top. I used to use used ATF or motor oil as
it was cheap, but burning olive oil is more friendly.

Charles

Pure bull****. *

Yep. That's what I was thinking. Funny how many OA welded steel
aircraft are still flying. I've been up in a few. My only real
question is wether they were built of 4130 in 1942, or something more
mild. Wasn't Mike Horowitz using 4130 and an HF torch on his Dyke
delta?

In any case, I thought that website was really quite humorous. Its
amazing how much wiz-dum there was on a site dedicated to building...
a bicycle. Well, bicycle-thingie.

Convention be damned when I get my OA cylinders (and if the snow ever
melts)! I'll weld it, test it to distruction, beat the hell out of it,
run over it with my truck, pump it full of air, and if it still looks
good, seek the comments and experiences of you folks. And then I'll
probably beat on it some more and report my results.

Boulder, CO is getting boring. The Kenetic sculpture race was
cancelled this year. Time for me to take up the torch (ha) and
reintroduce a little whackiness... oh yea, and practice my welding
for that homebuilt project.

Happy New Year Everyone,
Harry "90% mad scientist" Frey

"cavelamb himself" wrote in message ...

Structural brazing works just fine - if done correctly.

But too much heat causes the brass to migrate into the grain
of the 4130 - resulting in cracks.

It HAS to be done right.
And there is no way to tell afterwards if it was or not -
until it breaks.


Richard

I meant while the part was in service. If an engine mount was brazed, and there was an engine fire, would the braze
joint fail (come apart) where a welded one would hold?

On Jan 2, 9:58 am, wright1902glider wrote:
I thought that website was really quite humorous. Its
amazing how much wiz-dum there was on a site dedicated to building...
a bicycle. Well, bicycle-thingie.
---------------------------------------------------------------------

The website's attitude is fairly common among folks who have just
discovered the practicality of human-power as a mode of
transportation. Even Henry Ford considered the use of automobiles for
'personal transportation' as a deeply flawed philosophy, pointing out
that no society could afford it (circa 1885) which was why his initial
interest was in using internal combustion to power farm machinery
rather than cars.

Bikes are an interesting engineering challenge, especially in the area
of strength-to-weight. The market for light-weight, efficient chain-
driven 'safety' bicycles provided the financing -- and the intellect
-- for the materials developed for the one to be applied to aviation,
as proven by a couple of brothers from Dayton, Ohio. But most modern-
day re-discoverers of pedal power fail to do their home-work,
inflicting those who have with a constant stream of absurdities.

Anyone who has never built a bike probably should. At the very least
it will add years to your life :-)

-R.S.Hoover

On Jan 2, 9:20 am, Charles Vincent wrote:
wrote:

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

4130 is indeed hardenable by heat treatment or cold working. And 4135
even more so. I have hardened them both using both water and oil
quenches, though if you took the time to read one of the metallurgical
tomes on the subject, you would find they are spec'd as an oil hardening
alloy. Water has worked fine for me on small sections, though my
default quench (i.e. the bucket next to the forge) is water with a layer
of olive oil floating on the top. I used to use used ATF or motor oil as
it was cheap, but burning olive oil is more friendly.

Charles

OK. Must be that the chrome or molybdenum adds to the
hardenability. All my resources say that .4% carbon is necessary to
harden steels.

Dan

If you have any doubt as to the hardenability of any piece of steel , just
light up your TIG Torch and get it close enough to your steel specimen and
melt a small fly speck spot , turn off the welder and touch that spot with a
file , even on low carbon steel like 1018 you may find that the file will
give up just about as easy as the hardened 1018 will , hardness and loss of
ductility pretty much parallel each other , I have seen 4130 parts that
couldn't be filed or cut with a hacksaw , not good .
Best
Phil
wrote in message
...
On Jan 2, 9:20 am, Charles Vincent wrote:
wrote:

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

4130 is indeed hardenable by heat treatment or cold working. And 4135
even more so. I have hardened them both using both water and oil
quenches, though if you took the time to read one of the metallurgical
tomes on the subject, you would find they are spec'd as an oil hardening
alloy. Water has worked fine for me on small sections, though my
default quench (i.e. the bucket next to the forge) is water with a layer
of olive oil floating on the top. I used to use used ATF or motor oil as
it was cheap, but burning olive oil is more friendly.

Charles

OK. Must be that the chrome or molybdenum adds to the
hardenability. All my resources say that .4% carbon is necessary to
harden steels.

Dan

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.

I'm not sure where this all fits in, but most lightweight bicycle frames
have a reinforcing "lug" around the tubes at the joints. Are you talking
bicycles or motorcycles?
--
Jim in NC

"Charles Vincent" wrote

4130 is indeed hardenable by heat treatment or cold working. And 4135
even more so. I have hardened them both using both water and oil
quenches, though if you took the time to read one of the metallurgical
tomes on the subject, you would find they are spec'd as an oil hardening
alloy. Water has worked fine for me on small sections, though my default
quench (i.e. the bucket next to the forge) is water with a layer of olive
oil floating on the top. I used to use used ATF or motor oil as it was
cheap, but burning olive oil is more friendly.

After you harden it by quenching, do you then go though the normalizing, by
heating to "straw" color, and over a period of several minutes, remove the
heat, a distance at a time?

That was what I was taught eons ago, but only in reference to working mild
"God only knows" what type of steel. I'm talking in cars and trailers and
tractors and such.

I hear people talking about heating up the weld and tube to "cherry" and
that is not what I thought was the proper procedure, for normalizing. I was
taught that "straw" was attainable, by barely seeing any color in a
semi-dark area.

Can anyone straighten out my conceptions, and mis-conceptions, here? g
--
Jim in NC

Blueskies wrote:
"cavelamb himself" wrote in message ...


Structural brazing works just fine - if done correctly.

But too much heat causes the brass to migrate into the grain
of the 4130 - resulting in cracks.

It HAS to be done right.
And there is no way to tell afterwards if it was or not -
until it breaks.


Richard


I meant while the part was in service. If an engine mount was brazed, and there was an engine fire, would the braze
joint fail (come apart) where a welded one would hold?




Dunno, Mongo.

I guess it would depend on how hot for how long.

But remember that it takes an acetylene flame to braze in the first
place.

If if gets that hot in the engine room, whether the mount welds hold or
not is probably going to be a secondary issue...

Richard