Lack of fusion w/ TIG

[MikeR]

Hey guys. I am NOT new to running a TIG, but ran into a problem today that I'm not sure about.

I'm having to weld a small part of 5/8" stamped steel to a piece of 3/4"x5" CF flat bar. I did a trial weld, and it penetrated nicely into the stamped part, but bubble gum would've been stronger on the flat bar side. I've never had this problem before, and I'm wondering if I got a piece of steel that is an odd ball alloy. (odd ball to me is anything other than 1018 or 1020, etc) The puddle is nice and fluid. No arc wander.

I'm just wondering if you guys think it might be good to try another filler... maybe ER80S? 308L? 324L? I'm using ER70S-2 currently.

And because I know you're gonna ask......... 1/8" 2% thoriated, 13cfh, #8 gas lens, argon, 180 amps, machine is a 180SD, foot pedal, #10 shade in hood, brown hair & eyes, size 8 1/2 boots, coolant is mountain dew.

[MikeR]

Check it out, let me know what you think. This is going to be a pitman arm for my dads '27 Track Roadster.... 331" blown hemi. This is one car I don't want the steering to fail in!!!!

Picture one: note the clean break. It did not bend at all, just broke, and all it took was a screwdriver.

[MikeR]

picture 2

[MikeR]

Picture 3: I've never personally seen anything like this! It's almost like the flat bar turned to a saltine, just like Aaron said. You could hear it cracking when I broke it.

[MikeR]

I tried it again for good measure, again at 180 amps, but with a slight weave to hopefully tie the two together better. It was much harder to get apart, but I'm still not very happy with it since it's a highly stressed part. Is 180 amps not enough? Would I be better off with 7018 or 7024 with the same machine, or is this just not doable???

[MikeR]

oops, meant to post two more pictures.........here goes

[MikeR]

Picture 2

[chip hayden]

i think your weld to weldment differential is too great. try pre-heating the parts to @250F. do your root with gta if you wish. do your passes and cap and let it cool slowly in still air

[MikeR]

Are you saying that the bead is too small for the size of base metal?

[chip hayden]

yes. and making a wider bead won't help either. the vast difference in mass between the weld and the base metal causes the grains to solidify "poorly". you tend to "pack " more filler in with sma or gma so, you are less apt to see this pulling away occur[as in your photos].

[MikeR]

Chip, thanks! You were absolutely right. I ran a 1 1/2" long bead with 7024 @ 120 amps, and I couldn't get it apart with my 10 lb sledge hammer! (seriously)

Thanks again