304 SS Spray Transfer 100% Ar

By Lawrence (*****)

Date 10-03-2005 14:55

Couple of things.

Your post says spray transfer with 304.... Now 304 base material is commonly welded with 308 solid filler wire but I'm not familliar with 304 fillers.

If you ment to say 308 solid filler wire used in the spray transfer on 304 base material (substrate) I would say no, 100% CO2 is not recommended by any of the wire manufactures. 98%Ar-2%02 is the suggested shield gas for spray transfer with 308 fillers

Here is a nice link to a McKay 308 solid wire performance data sheet. It gives all the manufacture's suggested data.http://www.hobartbrothers.com/pdf/308_308L.pdf

The only time they support the use of 100% argon is when cut lengths are used for GTAW.

By cfrancis (**)

Date 10-03-2005 15:14

Thanks

Yes,,I meant 304 base metal with ER308lsi filler. I normally use 98/2 Ar/O2,, for GMAW Spray. I wasnt sure if one could use 100% Ar.

By - Date 10-04-2005 01:49

Lawrence is correct. The 2% O2 is there for arc stability. 100% Argon does not provide that.

By backpurge (*)

Date 10-04-2005 08:01

Argon and 2% oxy will be fine but if you can get hold of a cylinder of 2% CO2 in argon I would give this a go, you will find the weld comes up a lot cleaner due to the reduced surface oxides. Also CO2 carries a bit more heat across the arc than O2 so travel speeds will be up a bit and the weld generally penetrates beter and the surface sits a bit flatter

By - Date 10-04-2005 11:32

Hi Bob,
You are correct, the CO2 will give slightly, very slightly, less surface oxides, ( I would not say " a lot cleaner" ) but the oxides from the surface should be removed after completion of the weld anyway regardless of the gas used. The use of CO2, when using spray mode of transfer, is the increased risk of unwanted carbon pick-up. Please refer to The AWS Welding Handbook, Volume 2, Welding Processes, Eighth Edition, where it is recommended to use 99% argon- 1 or 2 % oxygen for spray mode of transfer for stainless steel. Advantages are: improved arc stability, produces a more fluid and controllable weld puddle, good coalesence and bead contour, minimizes undercutting on heavier stainless steels. I also refer to the Avesta Welding Manual where it speaks about Shielding gases for MIG welding. "To stabilize the arc, there is an additional 1-2% oxygen or 2-3% CO2 added to the argon. The higher contents of these gases will increase oxidation of the weld bead. The addition of CO2 will also increase carbon pick-up. The use of CO2 has a positive effect when position welding and with short arc and pulsed arc transfer." Although either gas can be used for spray mode of tansfer welding, I think that 98-2 is the better of the two. CO2 is better suited for short arc and pulse transfer welding behind 90% He- 7.5% Ar- 2.%5 CO2.

By backpurge (*)

Date 10-04-2005 13:22

Hi Chuck
Again it's going to be one of those points on which we will have to "agree to disagree", it just goes to show that welding is not such an exact science.

Different countries definitely have their own thoughts, I was in Germany recently and had a good chin wag with one of my colleagues from the States on the subject and it did highlight some major differences of opinion, and don't even get me started on what the guys in Germany think!!!!

Cheers - Bob

By - Date 10-04-2005 13:28

Thanks, Bob..
I didn't mean to sound argumentative. Recommended practices are just that..recommendations. My wife just "recommended" that I get up and clean the cat's (all 7 of them) litter boxes. Did I take that recommendation?? I know the consequences if I do, and the consequences if I don't, so I guess it's all a point of what the individual considers is best for him. Now, I have to go clean litter boxes.. ;-)

By backpurge (*)

Date 10-04-2005 13:34

How's this for a recommendation, get yourself a dog, that way you can make sure the cat's stay outside then there will be no litter boxes to clean.

Just a thought!!!

By - Date 10-04-2005 13:45

LOL... yeah, like thats gonna happen...My wife would put me outside before even considering those cat outside. Good thought though... is that a "recommendation"?? :-)