Question on 304ss

By vwjoegolf Date 04-11-2007 00:46

i am just laying practice beads on sheets of 11 gauge 304 and i was wondering the back looks like sugaring, more in some spots than others, could it actually be burn through. I am using TIG w/2 thoriated and 308 filler at somewhere between 60-80 amps i tried less thinking it was burn through, but cannot get a sufficient puddle with to little heat. I also tried pulsing it to lessen heat input. The surface of the bead also looks like it has striations on it, but when i go over the bead with out filler just to clean it up the weld looks a lot more like a ss weld should without those striations. Sorry if i am vague but i am a beginner with TIG ss and alum. thanks

By js55

Date 04-11-2007 13:52

Not sure about the striations but it seems that your backside is a combination of burn through and 'sugaring'. 11 gage at .1196" nominal wall (<1/8") is pretty thin. Its the burn through taking the material into the oxidation temperature range that causes the 'sugaring'.

By aevald

Date 04-11-2007 15:34

Hello vwjoegolf, Just a couple of things to add to js55's suggestions. You didn't mention the size of the filler wire that you are using for these beads that you are running. Consider this, when you are making a rod diameter selection, a given diameter of rod requires a minimum puddle size to properly melt the filler. If you are welding on the 11 Ga. material and using an oversize filler you will possibly end up burning through before you have enough heat to properly melt the filler. It may also stick or have a rough uneven bead profile. Heat sinks will probably help with the problem too. Try backing your 11 Ga. with a thick section of aluminum plate or if you've got lots of money, copper. This will also help to minimize the burnthrough by absorbing some of the excess heat. Just a few more thoughts to consider. Regards, aevald

By medicinehawk (**)

Date 04-13-2007 09:51

60 amps is too high imo. Try using a smaller diameter wire (.045) and really concentrate to keep the wire and the joint saturated with argon. Any twitch of the cup or pulling your filler rod out of the HAZ can produce sugaring and contamination. Try using a gas lense as well.