Safe to do gas welding on my frame?

Just in time. My next statement was going to be to ask any British guy how to properly fabricate a steel tube frame.

Heck even when you tig weld chromoly to do it properly you should pre and post heat with a torch to prevent stress cracks.

here are some tig faq's from lincoln ele.

TIG WELD 4130!
The Lincoln Electric Company, Welding Services. June 2000



Yes, you can TIG weld 4130 tubing up to .120" wall thickness easily with the techniques and procedures described in this bulletin. Answered are the top ten most frequently asked questions about TIG welding 4130 Chrome-Moly. These attached procedures apply to typical sporting applications such as experimental airplanes, racing car frames, roll cages, go-carts, bicycles, and motorcycle frames. The suitability of these techniques and procedures must be evaluated for your specific application.

Q. Can I weld 4130 using the TIG process?
A. Yes, 4130 Chrome-Moly has been TIG welded in the aerospace and aircraft industries for years. As with all welding, proper procedures and techniques must be followed.

Q. Do I need to pre-heat?
A. Thin wall tubing (< 0.120" wall) applications do not typically require the normal 300ºF to 400ºF pre-heat to obtain acceptable results. However, tubing should be at room temperature (70ºF) or above before welding.


Q. What filler material do I use?
A. Although there are several good filler materials, ER80S-D2, is one you should consider. This filler material is capable of producing welds that approximate the strength of 4130. ER-70S-2 is an acceptable alternative to ER80S-D2, as is ER70S-6, although the weld strength will be slightly lower.

Q. When I use ER70S-2 filler material, do I give up strength for elongation?
A. Yes. The filler material, when diluted with the parent material, will typically undermatch the 4130. However, with the proper joint design (such as cluster or gusset, for example), the cross-sectional area and linear inches of weld can compensate for the reduced weld deposit strength.

Q. Why is 4130 filler metal not recommended?
A. 4130 filler typically is used for applications where the weld will be heat treated. Due to its higher hardness and reduced elongation, it is not recommended for sporting applications such as experimental airplanes, race car frames, roll cages, etc.

Q. Can I weld 4130 using any other filler metals?
A. Some fabricators prefer to use austenitic stainless steel fillers to weld 4130 tubing. This is acceptable provided 310 or 312 stainless steel fillers are used. Other stainless steel fillers can cause cracking. Stainless filler material is typically more expensive.

Q. Do I need to heat treat (stress relieve) 4130 after welding?
A. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots.


Q. Do I have to pre-clean 4130 material?
A. Remove surface scale and oils with mild abrasives and acetone. Wipe to remove all oils and lubricants. All burrs should be removed with a hand scraper or de-burring tool. Better welding results with clean materials.

Q. Do I need to back-purge 4130 material?
A. Backpurging is not normally necessary, although some fabricators do. It will not hurt the weld and may improve the root pass of some welds.
.

Q. Should I quench the metal after I finish welding?
A. ABSOLUTELY NOT! Rapid quenching of the metal will create problems such as cracking and lamellar tearing. Always allow the weld to slow cool.

More Information on TIG Welding Chrome-Moly 4130

Find out more about Lincoln Electric's professional line of TIG welders here
Or, check out Lincoln cut length TIG welding filler metals here

WELDING SPECIFICATION: Aircraft and Motorsports

GENERAL INFORMATION

Remove all oxides and burrs within 3" of weld area.
Acetone wipe to remove all cutting oils.
Assemble and tack weld in joint in a minimum of four (4) places with TIG.
Tubing should be at minimum temperature of 70ºF (room temperature.
TIG weld per parameters specified using Lincoln's Precision TIGâ„¢: The Power To Perform. 185, 275 or 375.

they have been oxy acetelyne welding hobby airplane frames out of chrome moly for a long time.anyone who is skilled at o/a welding can weld a frame up or modify it without having to worry whether the welds are going to fail or not,they aren't if you did it right.
plus when you do finally get a tig you will already have most of the skills built up by doing the o/a welding.
that's my .02 anyways.

leon

531blackbanshee wrote:

here are some tig faq's from lincoln ele.

TIG WELD 4130!
The Lincoln Electric Company, Welding Services. June 2000



Yes, you can TIG weld 4130 tubing up to .120" wall thickness easily with the techniques and procedures described in this bulletin. Answered are the top ten most frequently asked questions about TIG welding 4130 Chrome-Moly. These attached procedures apply to typical sporting applications such as experimental airplanes, racing car frames, roll cages, go-carts, bicycles, and motorcycle frames. The suitability of these techniques and procedures must be evaluated for your specific application.

Q. Can I weld 4130 using the TIG process?
A. Yes, 4130 Chrome-Moly has been TIG welded in the aerospace and aircraft industries for years. As with all welding, proper procedures and techniques must be followed.

Q. Do I need to pre-heat?
A. Thin wall tubing (< 0.120" wall) applications do not typically require the normal 300ºF to 400ºF pre-heat to obtain acceptable results. However, tubing should be at room temperature (70ºF) or above before welding.


Q. What filler material do I use?
A. Although there are several good filler materials, ER80S-D2, is one you should consider. This filler material is capable of producing welds that approximate the strength of 4130. ER-70S-2 is an acceptable alternative to ER80S-D2, as is ER70S-6, although the weld strength will be slightly lower.

Q. When I use ER70S-2 filler material, do I give up strength for elongation?
A. Yes. The filler material, when diluted with the parent material, will typically undermatch the 4130. However, with the proper joint design (such as cluster or gusset, for example), the cross-sectional area and linear inches of weld can compensate for the reduced weld deposit strength.

Q. Why is 4130 filler metal not recommended?
A. 4130 filler typically is used for applications where the weld will be heat treated. Due to its higher hardness and reduced elongation, it is not recommended for sporting applications such as experimental airplanes, race car frames, roll cages, etc.

Q. Can I weld 4130 using any other filler metals?
A. Some fabricators prefer to use austenitic stainless steel fillers to weld 4130 tubing. This is acceptable provided 310 or 312 stainless steel fillers are used. Other stainless steel fillers can cause cracking. Stainless filler material is typically more expensive.

Q. Do I need to heat treat (stress relieve) 4130 after welding?
A. Thin wall tubing normally does not require stress relief. For parts thicker than .120", stress-relieving is recommended and 1,100ºF is the optimum temperature for tubing applications. An Oxy/Acetylene torch with neutral flame can be used. It should be oscillated to avoid hot spots.


Q. Do I have to pre-clean 4130 material?
A. Remove surface scale and oils with mild abrasives and acetone. Wipe to remove all oils and lubricants. All burrs should be removed with a hand scraper or de-burring tool. Better welding results with clean materials.

Q. Do I need to back-purge 4130 material?
A. Backpurging is not normally necessary, although some fabricators do. It will not hurt the weld and may improve the root pass of some welds.
.

Q. Should I quench the metal after I finish welding?
A. ABSOLUTELY NOT! Rapid quenching of the metal will create problems such as cracking and lamellar tearing. Always allow the weld to slow cool.

More Information on TIG Welding Chrome-Moly 4130

Find out more about Lincoln Electric's professional line of TIG welders here
Or, check out Lincoln cut length TIG welding filler metals here

WELDING SPECIFICATION: Aircraft and Motorsports

GENERAL INFORMATION

Remove all oxides and burrs within 3" of weld area.
Acetone wipe to remove all cutting oils.
Assemble and tack weld in joint in a minimum of four (4) places with TIG.
Tubing should be at minimum temperature of 70ºF (room temperature.
TIG weld per parameters specified using Lincoln's Precision TIGâ„¢: The Power To Perform. 185, 275 or 375.

they have been oxy acetelyne welding hobby airplane frames out of chrome moly for a long time.anyone who is skilled at o/a welding can weld a frame up or modify it without having to worry whether the welds are going to fail or not,they aren't if you did it right.
plus when you do finally get a tig you will already have most of the skills built up by doing the o/a welding.
that's my .02 anyways.


I agree 100% with this....

leon

Nice work zed, thanks for the pic.

ok here's what I did today. what do you think? I'm a little concerned if I got enough penetration. a beat on it with a hammer as hard as I dared without denting it and nothing gave way. This is the R side of backbone.

this is the L side of backbone

R side again with different lighting. Note the shadow along the edge. I think I made the frame tube thinner here. Kinda dug a trench with the torch. problem?

Back side. not much penetration visible. not sure what it should look like tho.

First and third pic looks ok, second pic looks like you were moving a little too fast with the torch.
Welds are a little undercut but will still be strong and ok for bracing etc, maybe need less gas pressure, go a bit slower or either bigger rods or less heat so you can get more build up (or go back over with another run).

Fourth pic is normal, Best to weld both sides if access is possible.

Hard to see in this pic but no there's undercutting.
Never really gonna get a raised bead when welding in to troughs as the capillary action draws the molten metal up the sides.
Been gas welding since i was 10 but still manage to do some dodgy looking welds from time to time, Best thing with gas though is that you can go back to pretty them up, Don't really get a second chance with stick or mig.

thanks. I used a 3 tip. Would a smaller tip work better in the trough? I tried size 1 first, but couldn't seem to get enough heat. however I think my 1 tip may be worn out. I can't get a really nice sharp flame with it anymore and cleaning does'nt help.

I've just been at it again. I'm getting better results now. The second pass helped a lot too. wider, thicker welds.