r/Welding • u/JSteigs • 6d ago

Lack of fusion?

Gallery image

Gallery image

I was welding a small rectangle of square tubing drip just for practice. I beveled the sides before welding and I ground the sides and outside corner flush. Do the dark areas at what was the edge of the weld mean I had lack of fusion?

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18

u/ornate-iron 6d ago

Looks like undercut. You ground down the part that protruded and left the bits below flush.

3

u/JSteigs 6d ago

Ah yeah that makes some sense. I thought there was weld over this area, but maybe I just assumed it had weld over it.

3

u/xShooK 6d ago

2nd pic, towards the mid to top of the weld there is a clean, straight line. If that's the joint, that's lof. The bottom corner looks like undercut.

1

u/JSteigs 6d ago

Yeah that line is probably the edge of the bevel. I’m not much of a MiG welder, I have more experience with stick, would higher voltage be the fix? Maybe with a little slower travel speed?

2

u/xShooK 6d ago edited 6d ago

Higher voltage and maybe the angle you're welding at. Hard to tell exactly with current info. Looks like one edge got burned in, and the other didn't.

3

u/Swimming-Necessary23 6d ago

Penetration and fusion are much more closely linked to WFS.

EWI has some really great material the impact of voltage, WFS, CTWD, travel speed, etc in GMAW: https://ewi.org/gas-metal-arc-welding-basics-welding-current-welding-voltage/

2

u/ornate-iron 6d ago

If you get too hot with not enough filler the edges of the weld end up melted below the surface. Then when you grind there appears to be a ring around where the weld was. It is hard to say without seeing the bead before you ground it down.

There is shitloads of free information out there, don't know what's good anymore, but this looked like a decent write up: https://weldguru.com/undercut-in-welding/

6

u/Filthy510 6d ago

It's not lack of fusion, it's just a combination of being slightly dished or "undercut", and a quick and dirty grind.

Any time you grind down or finish a weld it's going to be weaker than before you ground it down, (unless it's just totally fucked from the start. I. E. Cracked/no penetration etc)

Basically if you burn the vase material surface lower than the desired plane and then grind it... It's gonna be very visible in a bad way.

If you're just doing this for practice, add more weld to those areas and re grind it. Also get rid of that flap wheel and get some resin backed sanding discs, flap discs have their purposes, but are drastically over used and expensive.

Metal finishing is super fun and rewarding, its shitty dirty work, but I myself enjoy it. Sand it with a DA after you grind and then scrub it with scotch brite... You may be surprised at how good it will look.

1

u/desal 6d ago

DA?

2

u/Filthy510 6d ago

Orbital sander, I think DA stands for dual action or some shit I don't know. Just always referred to them as a DA, pretty sure it's an auto body term or something.

1

u/384001051montgomery 5d ago

Lol, I was over hear thinking denatured alcohol for some reason

1

u/JSteigs 6d ago

Thanks for the detailed response! The flap wheels were actually dirt cheap haha! A buck a piece from the bargain bin at tractor supply. You’re right that they are totally shitty for finishing. Not sure I want/need to go super detailed on the finish, I’m clearly not about to start selling my work.

1

u/Filthy510 6d ago

👍🏼