Just a thought....
How is the quality control of your weld wire? I se you listed AWS specs, but take a look at the cert from the manufacturere of the weld wire, and store you weld wire in an over, or humidity controlled storage unit. Improperly manufactured weld wire may have impurities in it witch may down the mfg process may cause discontinuities when the NDT inspector finds them.
Almost all electrodes used for GMAW of steels have deoxidizing or other scavenging elements (cleaning agents) added to minimize the amount of porosity and improve mechanical properties. The use of an electrode wire with the proper amount of deoxidizers is most important when using oxygen- or C02-bearing shielding gases. I'm not sure if this applies to Argon purging as well though.
The electrode also needs to match the tensile or yield strength of the base metal, depending on which criteria has been used for the design. This is usually the first criteria with plain carbon and low-alloy steels, as well as with some aluminum and magnesium welding applications.
Some of the factors that affect porosity are moisture in the atmosphere, contamination of shielding gas, welding position, welding parameters, contamination of base or filler metal, and surface cleanliness.
Any welder struggles with the porosity problem and has developed solutions which vary in effectiveness. Some of the porosity factors are:
No cleaning prior to welding
Mass cleaning of surfaces in the weeks prior to fabrication
Local cleaning of weld areas immediately prior to welding with coated abrasives
Local cleaning of weld areas immediately prior to welding with wire brushes
Strict use of iron-free coated abrasives
Strict use of fine wire brushes
Hope this helps in any way possible.
Rob
