Fillet undercutting

[PSweeney]

Havig some trouble with undercutting on fillet welds, any pointers ? Think i mave current a little high to get each piece to puddle. Welding 5mm plate to a piece of tube 5mm wall using about 120 amps
Thanks
Phil

 

[tedmagnum]

Angles ?

 

[hotrodder]

Pics would be helpful in narrowing down the exact cause... underfilling the weldpool, angles of attack wrong, arc length too long etc. Welding over millscale can cause it too. 120A doesn't sound excessive but while i may be reading to much into it this...

Think i mave current a little high to get each piece to puddle.

is leading me to suspect arc length as you're looking for one weldpool at the root of the fillet. As arc length increases it fans out and arc voltage increases i.e. more heat but not so focused. It's also an easy one to lose control/track of when welding around tube/pipe as the angles of attack are constantly changing

Oh, what size filler wire are you using, it'll help decipher the pics

 

[PSweeney]

angle and arc length is something I've struggled with being new to TIG. I'm using a 2.4mm rod. I'm focusing the arc into the root but it is the outside edges of where the arc is closest which are puddling first. Normally on a butt or lap I will turn the current down so I can go slower and concentrate on arc lenght but fillets seem to need more amps to focus the arc into the root, hence it all gets a bit frantic. Material is ground clean also.

Will get some pics up tomorrow when I'm practicing again, thanks for the comments.

 

[Rrunnach]

If you are welding joint in 2F position, invert joint to 1F position, then see how you get on with 1F. Assess and, if ok, which it should be, do same at 2F........it really is a dawdle!!

 

[langy]

angle and arc length is something I've struggled with being new to TIG. I'm using a 2.4mm rod. I'm focusing the arc into the root but it is the outside edges of where the arc is closest which are puddling first. Normally on a butt or lap I will turn the current down so I can go slower and concentrate on arc lenght but fillets seem to need more amps to focus the arc into the root, hence it all gets a bit frantic. Material is ground clean also.

Will get some pics up tomorrow when I'm practicing again, thanks for the comments.

I wouldn't be using 2.4 rod for a start, what tungsten do you have in ?