Hi zinnan

I am assuming that the gas is 95% Ar 5% CO2. Just confirm this please. From my experience, the type of wire you mention is not more prone to porosity that any other type of steel wire, so the posibilities from my experience are:

1) Bad batch of gas. (Typically has moisture contamination.)
2) Bad batch of wire. (This may sound crazy, but once had wire that contained gas pores inside the wire itself!)
3) External contamination of the wire.
4) Amperage / Voltage settings too high. (Tends to "blow" gas into the weld along with the spray transfer arc.)
5) Problem with the gas nozzle. (If the gas comes out in a "jet" rather than as a "blanket", it can blow into the weld. - Should not happen on two different weld guns though.)
6) Very cold weld settings that do not allow gas bubbles time to rise to the surface. (This will in all probability also result in LOF / cold lap defects.)
7) Poor welder technique. (Should not happen to two different welders though.)
8) Leaks in the gas line. (Should not happen to two different weld set-ups.)

Maybe other guys can add to this, especially on the welder technique issue.

Regards
Niekie