Brass welding is tricky
I personally use tig when welding brass. I have never tried to weld brass in AC(always dc). You want to bevel atleast 2/3 the gauge of your sheet. Bevel width would be a 45 from bevel depth. Keep your argon high I keep mine around 35 but I don't pay for it my employer does. If you have pre flow and post flow crank them up also. My preflow is in miliseconds so i keep it around 4. My post flow is in second I keep it around 6. You will notice the bronze puddle gets bigger as you move. I personally use a pedal as my remote. You can let off much faster then any hand remote.
Penetration is always an issue this is why we bevel brass. Some people preheat brass. That all depends on how thick the brass is. If your using thin gauge material like that you wont need to preheat. Preheating will warp your sheet especially if it has bent flanges from the break.
Back your welds.
Always clamp something behind your weld in the event of blow through. I use aluminum to back brass welding. Backing your welds will also act as a heatsink an minimize warping.
Pits:
Pits need to be ground or drilled out and filled correctly
If you have the luxury of having a pulser this is ideal for brass welding. Pulsers in general have 4 settings 1. Pulses Per Second (PPS) 2.Peak Time 3.amperage 4.Background amperage.
amperage would be the high point of the pulse
background amperage would be the low point of the pulse
pps would be how many times a second it goes high low high low etc
peak time is how long the pulse is at the high point.
This is good for a few reasons
1.Puddle size will stay consistant because the weld is hot cold hot cold etc
2.Color will stay CLOSE to matching because its not burning out all of the alloys
3.Pulser will automatically coin welds if configured right.
I use 2% thoriated tungston but thats up to you I wouldn't use anything less then 3/32 since brass burns so hot
See the puddle connect then add wire other wise you will wind up with pits.
Light gage material like that can even be fused.
Keep your max penetration on the plus side
A Smoke eater and a respirator will become a requirement the more often you weld brass
I dunno I'm sure I left something out but at this point i'm rambling off topic.
I've done all sorts of brass tig welding.
Here is my employers website you can see some things I have done with brass.
http://crescentmichaels.com/Its hard to have a structurally sound weld that matches
I say its hard because its tricky to get both color and strength
Good Luck
Chris