tungsten exploding

[shawn]

i was welding a catalytic converter to the exhaust pipe on my jeep and the tungsten keep exploding on me. what would cause that? i'm using 2% thoriated and have the argon running about 15lpm

[performance]

#1) 15 lpm is probably way to much, turn it down to 7. Make sure you hear it coming out and nothing is kinked.

#2) You have your polarity reversed. This will vaporize an electrode given the right conditions. Your torch should be negative.

[performance]

#1) 15 lpm is probably way to much, turn it down to 7. Make sure you hear it coming out and nothing is kinked.

#2) You have your polarity reversed. This will vaporize an electrode given the right conditions. Your torch should be negative.

#3) You are using a mixed shielding gas with C02 in it. Use Argon only. Its possible to have a contaminated tank.

These are the three possibilities that come to mind.

[shawn]

i'm using 100% argon.

why would the tungsten be blowing up now when it was welding fine with just the exhaust pipe? i had to add in a section of pipe to move the cat further back and it welded fine but when i added the cat is when the tungsten started exploding

[shawn]

so i should be welding with the torch in the negative slow all the time? thought that was just for aluminum

[Rodsmachineshop]

I got a bad argon once destroys your electrode and 15 lpm is way to hi.

[performance]

AC is for aluminum, not DC, though a highly experienced tig welder can use DC + for aluminum with a mix of helium and argon, no DC current is great with aluminum.

DC+ will blow through the tungsten, especially if it is small tungsten as the electrode gets very hot. To weld with it, you need large tungsten to weld with very low amps.

I believe you have a PowerUltra, and it is not designed for aluminum.

[shawn]

ya i have the powerultra and no i'm not trying to weld aluminum. so lemme make sure i got this right. for welding any metal with a dc tig my torch should be in the negative slot and my ground should be in the positive?