[rnln]

thanks guys.

Rusnak,
On this bar, I was trying to increase wire speed to get lot of weld (puddle) but a tat higher wire speed, will make it pop.

I also tried smaller bar (you can see the smaller bar behind in one of the pics). Maybe the smaller bar is softer material, for the same setting, that smaller bar melted quicker and created puddle. Also, it's easy to burn through it.