We have a problem with porosity.

Machine Type Motoman Robot
Control System YASNAC
Control speed 30 TO 70 cm/min
Weld wire type Lincoln / supra mig vltra / En 440 G4Sil /AWS A5.18 ER 70S-6

Weld wire feed rate Unknown at this time

Type of Gas 8% CO2
92% Argon
17 to 20 liters/min
Blend (Mison 8)
Gauge of steel 3 to 50 mm
Type of steel Domex, Hardox, Weldox

Here's some good information: Common Problems and Remedies for GMAW (http://www.lincolnelectric.com/knowledge/articles/content/gmaw.asp)

Alfred E Neuman comes through again.

Excellent web site and great place to start.

Thx JSW

I am not a welding expert. Several years ago, however, I needed a definitive explanation of weld porosity. An old Navy buddy sent me the attached. Hope it helps.

Looks good too.

Will review this with the welding team and see where they want to start.

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

Miller Electric http://www.esabna.com/html/eu.cfm

ESAB http://www.esabna.com/html/eu.cfm

OR try the welding Teacher http://www.weldingteacher.com/

This site (http://www.esabna.com/EUWeb/OXY_handbook/589oxy10_4.htm) discusses oxygen content in steels as a contributor to porosity.

Jennefer doesn't you company have specifications for controling purchased meterials?
additionally most of your welding filler metal when use properly have enough deoxidizer built in to make processing oxygen not usually an issue, but it can be fun to explore. I'd bet more on basic stuff such as elctrode extention, conamination on base material, wind, maybe even the torch it's self did anyone chech the physical/machanical condition of the equipment- like- is the insulator intact? All to often I see folks the that just because we have robwelder we have a cure-all -- WRONG

Not to be a fourm hopper post your question in the follow forum these guys are the top food chain in welding. http://www.aws.org/cgi-bin/mwf/forum_show.pl

Hope this helps

oxygen in steels is usually controlled at manufacture- but when welding most filler metals when used correctly have additional deoxidizers built in to help ensure this is not a problem.

Jennefer doesn't you company have specifications for controling purchased meterials?
additionally most of your welding filler metal when use properly have enough deoxidizer built in to make processing oxygen not usually an issue, but it can be fun to explore. I'd bet more on basic stuff such as elctrode extention, conamination on base material, wind, maybe even the torch it's self did anyone chech the physical/machanical condition of the equipment- like- is the insulator intact? All to often I see folks the that just because we have robwelder we have a cure-all -- WRONG

Not to be a fourm hopper post your question in the follow forum these guys are the top food chain in welding. http://www.aws.org/cgi-bin/mwf/forum_show.pl

Hope this helpsYes, supplier controls can help, yet things can happen to batches or lots that slip through. Our poster didn't say how long the problem has existed, if it's happening across lots, or how much of that analysis has already been done. So it could be worthwhile to include all the aspects, and methodocally pursue them in a reasoned order when solving the problem.