Best welding rod (tig) for welding 4130 chromoly tubing

[zkoobs1978]

Does anyone know the best (strongest) rod for welding 4130 Chromoly tubing. I am building mini sprint chassis.


Thanks,

Zeb

[ASKANDY]

ER80S-D2

Lots of stuff here on that subject.

Andy

[Aerometalworker]

Er80S-D2 is used in aircraft weldments that are heat treated, ER70S-2 is used for non heat treated. Of course standard practice involves post weld tempering or oven treating.
-Aaron

[FM117]

Zeb,
You will not get agreement on the answer to your question.
Some use ER70 others use ER80. On the frame itself I doubt
you'll be able to do post weld heat treating.
I use ER80 and don't believe in the practice of torch annealing
the welded joints. I do use lowest heat needed an don't "hurry"
the weld along.
Opinions vary....do lots of reading and make your choice.
Will also mention that the Lincoln motorsports welding program
falls in the ER80 camp.
Dave P.

[Showdog75]

Murf McKinney who builds most of the NHRA Top Fuel chassis uses ER80S D2 and doesn't stress relieve all the welds . If it's good enough for 8000-10000 horsepower I'd say it would work for you .

[ASKANDY]

ER80S-D2 is a higher strength steel filler that contains 1/2% of Molybdenum and more closely matches the strength of the 4130 than the ER70. You can stress relieve the weld joint if you wish but even some of the top drag chassis builders don't do it. Heat treating is only somewhat useful and relies on how much base metal is diluted with the filler. Normally, heat treating is done with 4130 filler and on thicker weldments. Keep your arc lengths as close to the joint as you can and do not overheat by using too much amperage but make sure the toes of the weld are tied in properly. With a mini-sprint chassis and the amount of triangulation that is used in the tube layout, you should be fine.

Like Dave said.
You will get many answers here....

Andy

[Aerometalworker]

Murf McKinney who builds most of the NHRA Top Fuel chassis uses ER80S D2 and doesn't stress relieve all the welds . If it's good enough for 8000-10000 horsepower I'd say it would work for you .

Funny, notice where that got them? Ever see the failed welds on the Force teams cars? Hmmmm.
-Aaron

[trstek]

You can use coat hangers...

The important point here is that on a race vehicle, the design is light weight, close to the limit of strength / failure. Some, but not a lot of "extra" safety margin.

Sooooo, what that means is, you race, you inspect, you race, you inspect, repeat until the frame is wore out...

Where folks get into trouble is they under design, never inspect, or forget that life cycle deal.

If you want to be competative, weight is an issue, having a vehicle break up under you or worse yet, not protect you when you really need it like when you tangle with a wall or 3 or 4 other vehicles.

Just kiddding about the coat hangers by the way.

[Aerometalworker]

You can use coat hangers...

The important point here is that on a race vehicle, the design is light weight, close to the limit of strength / failure. Some, but not a lot of "extra" safety margin.

Sooooo, what that means is, you race, you inspect, you race, you inspect, repeat until the frame is wore out...

Where folks get into trouble is they under design, never inspect, or forget that life cycle deal.

If you want to be competative, weight is an issue, having a vehicle break up under you or worse yet, not protect you when you really need it like when you tangle with a wall or 3 or 4 other vehicles.

Just kiddding about the coat hangers by the way.

Coat hangers??? where the heck are you finding metal ones now-days??! We always called them RG-Black. However if given the choice between a coat hanger from 1940, and filler metal from china.......I would trust the coat hanger to at least be consistent!

[trstek]

I've got a closet full of them, first Grandpa's old clothes, then some of my pop's.

In years past we used them often on exhaust pipes with gas heat.

They actually work pretty good.

Back on subject, inspect, inspect and then clean and inspect. Think it is great the project is moving forward, no one teaches maintenance any more...

Hey Aaron, thought that would get a rise out of you

[Aerometalworker]

I've got a closet full of them, first Grandpa's old clothes, then some of my pop's.

In years past we used them often on exhaust pipes with gas heat.

They actually work pretty good.

Back on subject, inspect, inspect and then clean and inspect. Think it is great the project is moving forward, no one teaches maintenance any more...

Hey Aaron, thought that would get a rise out of you

Ha Ha yeah, I have seen the old hangers, they were made from some pretty soft iron to be able to be formed like they were, maybe it was just a simple low carbon drwn iron wire not too different from RG-45. For fun I should dig one up and have it scanned. The torch is pretty forgiving of filler, in fact the less alloying elements, the more fluid it seems to weld, kind of the opposite of electric welding. You know back in the late 1960's , most of the aircraft companies were using Oxweld 1 and Oxweld 65 for their tig welding on 4130?

[FusionKing]

what about using oxweld #32 cms or #7 for this Aaron? on O/A. What are they made of?

Also even the filler mfgs (Harris) say er80 is for use with post heat treat only. Never mind what they think.

BTW...I'm not sure I would trust MY life with the stupid@$$ practices Mckinney did
IIRC he was even using the wrong material to begin with.
Somebody ought to post a link to that thread.

[Aerometalworker]

what about using oxweld #32 cms or #7 for this Aaron? on O/A. What are they made of?

Also even the filler mfgs (Harris) say er80 is for use with post heat treat only. Never mind what they think.

BTW...I'm not sure I would trust MY life with the stupid@$$ practices Mckinney did
IIRC he was even using the wrong material to begin with.
Somebody ought to post a link to that thread.

FK,
Oxweld 7 is basicly a drawn iron wire, and was the standard for most weldments in 4130 up to about 1/8" thick. Thicker then that Oxweld 1 was usually suggested and is a "low alloy" filler. 32CMS was heat treatable as was used in areas that would recieve a heat treat above the normalized condition and contained chromium, moly, etc. etc. Of course there was no hard and fast rule as it has a lot to do with the joint configuration and application. In WW2 military aircraft design prints you see mostly oxweld 7, with oxweld 1 being used in some heavy critical areas like wing attach points and 32cms on heat treated gear assemblies. It should be noted that the tensile strengths of the pure filler is not what the weldment tensile strength ends up being due to intermixing of the alloys. the AMS did a bunch of testing years back on this for an aerospace firm, I dont have the numbers in from of me right this second but they ended up being much much higher then the filler tensile strength.
Now back to Tig, in a letter I have from one of the aircraft companies from 1964, it explains why they chose oxweld 65 ( now called er70s-2 ). It was due to the ductility and elongation of the material. They WANTED a softer material since the area of reinforcement ( weld bead ) more then makes up for the slightly lower strength compared to the base 4130, and the end result was a more ductile weldment. Unfortunately not much has been done in recent years as far as company sponsored engineering help as 4130 tubing is now mostly reserved for engine mounts and such. However the materials have not changed, so I tend to follow the trends from when the material was in the prime of its use in a critical application. I know im a bit of a "nerd" about this, you should see my library on this subject!

On a personal note, the old 32cms ( now replaced with RG-65 ) makes some beautiful welds if you ever section them or have to machine on the material!
-Aaron

[trstek]

ok... some pictures of the frame and welds...

So, where will you be running?

Who will be piloting this here craft? New to it, coming from Kart' s, whats the story.

A little bench racing is in order after a question like one that was asked.

[Aerometalworker]

ok... some pictures of the frame and welds...

So, where will you be running?

Who will be piloting this here craft? New to it, coming from Kart' s, whats the story.

A little bench racing is in order after a question like one that was asked.

Yeah interested here too! And what was your final choice for materials?