Background on my problem: I weld this one particular part at work pretty frequently. It's an L-shaped bracket with a hole in it where a pin goes through it at a right angle. The bracket is maybe 3/16" thick and the pin is about 1" in diameter. Both pieces are carbon steel, nothing special. Both pieces are adequately cleaned. The process is TIG welding with a Miller Syncrowave 250. The equipment is functioning just fine. Using ER70S fill rod.

We have cracking issues sometimes with the welds on these. It shows up immediately. You have to make three beads to complete the weld, and it almost always shows up in the third and final bead, sometimes the second one. You'll just wind up with a crack that runs the length of about half the weld. The only thing that seems to help it is to turn down the amps on the welder, but sometimes even if you turn it way down (we are usually welding around 200A) and you are at 175A it still cracks. If you run over it a second time with more fill rod it's fine.

The weird thing is some nights it's not an issue at all, and sometimes it seems to happen on every fifth or sixth part. Anyone have some suggestions on what's going on here? It slows me down getting work done, because I have to pause after every part and look at it and be real positive it doesn't have a crack rather than just pulling it out of the jig, tossing it on the table, and moving on to the next piece. I could be turning out a lot more of these things if I knew we had the problem licked.

Thanks to all in advance,
Tom