4130 tubing welding question

[Steve Weir]

When joining two pieces of 4130 tubing together in a 90 which joint would be stonger 45 degree cuts welded or a fish mouth with the end of the tube extended and capped? Is this a wash? Both joint would have a gusset added. Thanks for any help.

 

[jebthereb]

fishmouth?? it that a term for a saddle weld?
as to a wash pass, i would figure that no matter what you would need filler wire for the joint.

 

[Earthboundmisft]

45 is cleaner. Strength is about the same. Especially with a gusset.
Jeb, the "wash" was in reference to 'no difference' between the two.

 

[jebthereb]

ahhh..
notes made in things to remember book...

 

[Steve Weir]

Thanks Mike, I am leaning towards the 45, it is a cleaner joint.

 

[JEFF TIPTON]

Pazmany showed in his plans for the PL1 rudder pedals using a flat plat trimmed to oval shape of the tube cut at the 45 degree angle and welding it in place between the two tubes.

 

[AirScooter]

Just make sure it is welded with ER70S-2 or equivalent filler wire. I would go with the 45 degree joint, in my mind it would have a little more weld length than the fishmouth or cope.

 

[Mike G]

Don't forget to pre heat.
Mike G

 

[L_Butler]

Pre heat

Pre heat

While pre heat is generally desirable with heavy parts (over 1/2" thick) of 4130 steel, it is not usually used on tubing unless 4130 filler rod is used. The preferred filler rod on 4130 tubing is ER-70S-2. There is a slight loss in strength using ER70S-2 however it is a much easier rod to weld and is less likely to produce porosity or cracks.

If you are adding gussets, then the additional strength of the 4130 filler rod is not worth the aggravation of preheating to prevent cracking.

Here's a link to an American Welding Society article on welding of NASCAR frames: http://www.aws.org/wj/apr03/AWfeature.html The article includes information on filler material, weld process, etc.

Larry

 

[JEFF TIPTON]

If TIG welding the part this site is also useful.

http://www.millerwelds.com/resources/articles/Best-Practices-for-GTA-Welding-of-4130-Chrome-Moly-Tubing

 

[Steve Weir]

Thanks Larry and Jeff those are a good reference. Thanks everyone for your help I appreciate it. I have ER70S-2 and ER80S-2 and will use the ER70S-2 Tig.