Welding question

[Bcone1381]

Olm, I've never seen welding like that done on airframes, but I'm a novice.
___________

Welding Wars.....It's Human nature to collect evidence that supports what we want and believe and dismiss evidence that does not support it.

I've seen comparison of 4130 steel joints tested that were welded with TIG and OA. When the joint was stressed the TIG joint that was not normalized afterwards with an OA torch broke instead of bending at the heat effected zone while The OA joint bent over but never broke.

So I want to believe that and dismiss other evidence that says normalizing TIG is not needed. I am often wrong, so now I keep these data pionts in mind and wonder and look for more data to build a truthful EAB Industry Best Standard picture.

And when I saw the Cold Weld video it looked very interesting but I see a very tight heat effective zone and believe it suitability for 4130 steel needs to be investigated with destructive testing.

Bob likes OA due to what I shared and that forms my viewpoint and concerns about TIG. But why does EAA TIG worskhsop say Normalizing is not required? I'm Curious, and I know its from a TIG guy who may have a truth, but possibly a view that he wants to believe dismissing other workshop evidence that exists. I'm watching, listening, collecting data in the pursuit of truth and IBS (Industry Best Standards).

[Sir Newton]

B this thread has me laughing my ass off.
For one reason & one reason only. There is not one ! single welding symbol used on ANY of Bob's blueprints. & the entire fuselage is a welded structure! Lol

[sjt]

Wyatt Swaim, a.k.a. "Mr. Tig" recently passed away.

I am no expert but he was.
I except his logic:

https://youtu.be/wVrdST1pXRk?t=2214

this is about 37 minutes into video

summary:
Do not use rosebud

He did not use an OA torch after tig because the before condition of 4130 is 90 KPSI. If you use a torch the whole tube area is now no longer 90.
You spent money on something was 90kpsi and then you go out of your way to reduce it. If you anneal 4130 the tensile strength goes down to 52kpsi.

At a different part in his video he points out that when a red hot metal is exposed to oxygen it becomes carburized. That can cause stress fractures at some point.


bottom line:

no rosebud

ers80sd2-.045

Oxy Acetylene perfectly fine process.


Tig is perfectly fine process.


He questions logic of not taking advantage of the tig process by going out of your way to change 90kpsi metal to 52kpsi metal.

[jaredyates]

We've talked about all of this before, sometimes several times, but I'll retell the story of testing welds at our local community college. We didn't have a huge sample size, but my professional tig welder friend made up some sample joints, and I unprofessionally welded up the same type of joint with an OA torch. We took them to the college and load tested the joints in tension. If you didn't have numbers and only saw the way the pieces broke, you'd see that the TIG snapped right outside the HAZ, as it is said to do. The OA piece's failure would be better described as "tearing" and didn't seem to be associated with any of the weld beads or HAZs. But, the numbers are important, and the TIG piece broke at 7000 pounds, while the OA broke at closer to 5800, if I remember correctly. So while the TIG piece might have looked inferior, it was a stronger joint.

[Bcone1381]

I like data. Thanks Jared.

[sjt]

That confirms Wyatt Swaim, a.k.a. "Mr. Tig" assertion. A rosebud changes 90kpsi tensile metal to 52kpsi metal. (math is not exact)


I have been using both processes. I do not have a dog in the fight. This is just an academic pursuit for me. Both processes will make a good airplane.

I myself like to spend money, and a TIG machine + argon bottle will achieve that goal.


That said, using a gas lense with a one inch tungsten stick out is the bee's knees

[alaskabearhawk]

Ok...one more time. The three clusters on the left were welded with a Miller Dynasty 200DX TIG using a 2% thoriated electrode and 1/16th ER70S2 rod. The one on the right was O/A welded with a Meco torch and RG45 rod. Material was 3/4in dia .035 4130N tubing. No post-heating, "normalizing", annealing, stress-relieving, fussing, etc. on any of them. I welded them at a room temp of 70F and allowed to cool naturally at least 5min with no breeze. I beat the stuffing out of all the clusters with a 5lb hand sledge. No cracks, no failure. "Cold welding" as a method isn't listed in AC43-13B so I would think twice before using it on any component. In my opinion the key to a good weld boils down to three things: Practice, practice and more practice. YMMV.

https://www.youtube.com/watch?v=ZEA-g8sMynY

20230201_145853.jpg20230201_145919.jpg

[Sir Newton]

Not one weld failed. something to think about

[TimTall]

Ok...one more time. The three clusters on the right were welded with a Miller Dynasty 200DX TIG using a 2% thoriated electrode and 1/16th ER70S2 rod. The one on the right was O/A welded with a Meco torch and RG45 rod. Material was 3/4in dia .035 4130N tubing. No post-heating, "normalizing", annealing, stress-relieving, fussing, etc. on any of them. I welded them at a room temp of 70F and allowed to cool naturally at least 5min with no breeze. I beat the stuffing out of all the clusters with a 5lb hand sledge. No cracks, no failure. "Cold welding" as a method isn't listed in AC43-13B so I would think twice before using it on any component. In my opinion the key to a good weld boils down to three things: Practice, practice and more practice. YMMV.

https://www.youtube.com/watch?v=ZEA-g8sMynY

20230201_145853.jpg20230201_145919.jpg

Which one was on the left?

[alaskabearhawk]

Oops! I corrected it. The three on the left are TIG, the one far right is O/A.

[sjt]

Both TIG and OA produce acceptable results. With the OA sample you can see what Wyatt Swaim refers to as carburizing. He does not recommend using a rosebud on TIG . If you did it would create the same dark area on a tig weld. TIG does not have carbon and oxygen flying around glowing red hot metal. The carbon and oxygen change the chemical composition of the surface of the 4130 tube.

From what I remember of the recent EAA webinars, the problems are flying into a cloud, teflon tape on gas fittings, and not bolting the prop on correctly.

There was another accident years back that was caused by the builder using plywood sheets from home depot for the wings. Probably not a consideration for Bearhawks.

[Redneckmech]

I mean a type of TIG welding, but the parts are not overheated and you have no problem with metal tention(or what they call it(sorry for bad English)) around the welds. Working with inox there is also no problem with metal deformation what is usual when you weld it with TIG. It is good type of welding for thin metals. Example video: https://www.youtube.com/watch?v=9IaLQ5uFLN0

This process would likely be similar to laser welding in the size of the heat affected zone. It would not be a good match for 4130 since the minimal heat input would encourage martensite formation and create a brittle zone at the edge of the weld. It would however be a wonderful process to use for stainless (inox) or thin sheets of low carbon steel.

Here is a research paper providing evidence of the need for increased heat input for laser welding of 4130 due to cracking:

https://www.researchgate.net/publication/343086515_A_Comparative_Study_of_Abbreviated_Heat_ Treatments_for_SAE_4130_Steel_After_Laser_Welding_ 1




On the ongoing discussion, I think this is about as close as we can get to politics on the forum without getting banned (-:

I think Paul has the right approach. On the thickness of tubing we are working with, practice matters more than process as long as the weld is allowed to cool slowly and is not made in a cold/drafty environment. Weld joints on aircraft are engineered with a significant safety factor to account for variations in weld quality and material. ER70s2, ER80sd2, RG45 as long as they are used with the respective processes reflected in AC 43.13 (section 4-86, page 4-54). and done by a skilled operator will provide a satisfactory outcome.

Everyone has their own opinions and preferred process, myself included. I have a good friend who used GMAW (MIG) when he built his airplane (not a bearhawk) over 25 years and 1k hours ago. Personally, I would not use that process on any aircraft or other structural application but it has obviously worked for him.

[jaredyates]

Just to reiterate, MIG is not an acceptable method for any of the Bearhawks. Surely anyone reading this knows that by now, but just making sure the last sentences can't be misconstrued.

[Redneckmech]

Thank you for that clarification Jared, I can see how my message could be misconstrued. I have updated my comment to reflect that it was not a Bearhawk and to provide clarification reflecting welding processes in AC 43.13. GMAW does not belong in any structural application.

[geraldmorrissey]

Right now I am fitting steel tubes to steel sheet metal ribs in the tail. .032 ribs to .035 and .049 wall tubes. I have been told in the past that a small gap should be built into the joints for gas welding, no gap for tig. What is a small gap? .010, .020. Is it dependent on wall thickness/diameter? I was able to find much info on 1" plate but little on the lightweight stuff we use.
Thx
Gerry

[alaskabearhawk]

This should help. A short video of a tool I made to check gaps in the clusters before welding: https://www.youtube.com/watch?v=pNHh6tj-j5Q

[geraldmorrissey]

Took in a oxygen bottle to get exchanged today. $30 for a 200 cubic foot cylinder. Cheap. Inquired about acedelyne, $135 for 145 cubic foot. Just had a price increase. The salesman said that propane and propane blend gasses are replacing acedelyne in cutting and welding processes. It's much cheaper. Acedelyne production and availability is shrinking. Thus the price increases.
Gerry
Patrol #30

[spinningwrench]

Welding discussions will be endless but I have gotten to know the welders at American Champion Aircraft where almost all parts of the airframe are MIG welded using a pulse technique. Turns out RANS, Kitfox, and Carbon Cub all use this approach on their airframes with no problems. It really is all about practice and technique. Welders at American Champion have to re-certify each year by welding typical clusters and then destructive testing. I have practiced using their technique and with their coaching and feel I could do an entire airframe but find the MIG approach requires an entire extra level of concentration because it goes so fast. That said I TIG weld exclusively when adding tabs to my airframe because the process is so controllable and not as likely to go bad as MIG potentially could. If I were in a production environment where cranking airframes out as quickly as possible is $$$ then I would fully embrace MIG welding as it is so much faster than TIG or oxy.

[jaredyates]

MIG is not an acceptable method for the Bearhawk line.

[sjt]

In the case of Mooney - which used mig - the process was much more complicated.
After mig they then took the entire fuselage - the massive weldment and placed it in a massive oven to heat it up.

I do not know the details of how long or what temp the oven was run.
Even if you knew the metallurgy, it would not be possible to make an oven that big.

[spinningwrench]

I can only speak to the fact that the local FSDO has approved it for American Champion on 4130 tubing via demonstrated competency and failure analysis. This now falls into their Accepted Methods and Practices for producing airworthy airplanes. All builders must build to their competency and comfort level. For most Bearhawk builders that will be TIG or oxy. I am not pushing any agenda or process merely stating facts.

[jaredyates]

I can only speak to the fact that the local FSDO has approved it for American Champion on 4130 tubing via demonstrated competency and failure analysis. This now falls into their Accepted Methods and Practices for producing airworthy airplanes. All builders must build to their competency and comfort level. For most Bearhawk builders that will be TIG or oxy. I am not pushing any agenda or process merely stating facts.

Implying that MIG is acceptable if the welder is in whatever sense 'good enough" can be misconstrued by a welder who thinks he is good enough, because after all he is a good welder, right? If there is someone who does have the required equipment, factory, and skill to use MIG safely to create an airframe, he doesn't come to a place like this to find out, so we don't need to tell him. There is a far greater risk of enabling someone who thinks he is- but isn't- than any potential benefit of saying it's possible, when for nearly any homebuilder, it is not.

The designer of our planes doesn't approve of MIG for our airplanes and I don't consider it consistent with the rules of the forum to imply that it is.

This is not an academic/engineering "what is technically possible" matter, but rather a "what someone might read and take out of context" matter. Eclipse jets are (were) friction stir welded in a factory. Does that mean we should talk about that method for Bearhawk construction? No, because we aren't building an Eclipse, or a Carbon Cub, or anything else. The design of the airframe includes dimensions, materials, and techniques. Deviation from any of those three means you are now the designer of a Bearhawk-inspired new thing. Some of our members have the chops to do that safely. Most of us don't. It is beyond the scope of the forum (except the appropriate section) to host discussions about design mods that are likely to compromise safety, other than to reiterate that they are not safe.

Homebuilt airplanes in mishaps are almost never falling out of the sky due to structural failures, because we build them as the designers specify. Let's keep it that way please.

[spinningwrench]

If Bob only wants to advocate gas or TIG welding I can certainly respect that. There unfortunately have been gas welding samples posted on the forum that are downright scary looking and I am surprised members don’t provide feedback. Is it because it’s an “approved” process.

[Frank]

"Scary looking" as in not pretty? Or "scary looking" as in dangerous?

[jaredyates]

If Bob only wants to advocate gas or TIG welding I can certainly respect that. There unfortunately have been gas welding samples posted on the forum that are downright scary looking and I am surprised members don’t provide feedback. Is it because it’s an “approved” process.

Please speak up any time you see something scary, whether it be a poorly executed approved process or anything else. Building a plane is a big job and we can all help each other. It may be that the poster doesn't realize that anything is wrong.