Welding chromoly..
Staging Lane
Joined: Apr 2005
Posts: 93
Likes: 0
From: Coastal NC
Welding 4130 chrome-moly is normally done with Oxy/Acetylene but thin wall can be welded with the TIG process. (If using a TIG use 2% Thoriated tungsten rod and 100% Argon). Filler would be 1st choice ER80S-D2, 2d choice ER-70S-2, 3d choice is ER70S-6, although the weld strength will be slightly lower. A 310 or 312 stainless steel filler can also be used.
4130 filler is only used when the weld will be heat treated. It has a higher hardness and reduced stretch, so it is not recommended for airplanes, race car frames, roll bars/cage, etc.
Thin wall doesn’t always require being stress relieved, but it is reccomended. Parts thicker than .120", require stress relieving at 1,100ºF. You can use an Oxy/Acetylene torch with a neutral flame but avoid making hot spots by keeping it moving and heating evenly.
Of course if you don’t care about specs I guess you could use a wire feed welder (MIG) with a stainless wire.
YMMV
4130 filler is only used when the weld will be heat treated. It has a higher hardness and reduced stretch, so it is not recommended for airplanes, race car frames, roll bars/cage, etc.
Thin wall doesn’t always require being stress relieved, but it is reccomended. Parts thicker than .120", require stress relieving at 1,100ºF. You can use an Oxy/Acetylene torch with a neutral flame but avoid making hot spots by keeping it moving and heating evenly.
Of course if you don’t care about specs I guess you could use a wire feed welder (MIG) with a stainless wire.
YMMV
4130 is used moderately in aircraft.its alot easier to work and safer to work for the ground crew then stainless steel. Theirs also a reason that chassis builders use 4130. like some of the others have said use pure argon and I've always used 70-S6 for the filler. The best filler rod you can use though is the same type of metal or stronger that your welding. Example 4130 or higher to be used in your situation. I might be wrong but the goverment seems to think that I'm right since they've had me welding there aircraft for the navy, and they get X-rayed before they go on the plane.
Staging Lane
Joined: Apr 2005
Posts: 93
Likes: 0
From: Coastal NC
You can weld it with a lot of things and a lot of different ways. But most auto applications are for roll bars. Welding it with a 4130 filler requires that it be stress relieved otherwise it may fail in an accident due being brittle. Also it has no fatigue strenght unless stress relieved so it could possiabily crack from chassie movement running around the track or to the Baja, what ever. The most common filler used everyday is probably some kind of stainless filler.
When my life or someone else's life depends on it I think it's worth the effort to do the job right. Of course if I were making a gate, a mailbox stand, or doing something non-critical like welding on my brother-in-law's truck, then I would use an old coathanger for a filler.
When my life or someone else's life depends on it I think it's worth the effort to do the job right. Of course if I were making a gate, a mailbox stand, or doing something non-critical like welding on my brother-in-law's truck, then I would use an old coathanger for a filler.
