whats the general reasoning for the dark sugaring on stainless welds? i tried adjusting amps, flow, and cup size, but nothing seems to do the trick

 

i was welding onto a small piece of 3" 304 with .065" wall that i did nothing to prior to welding...i know that with aluminum you need to clean the thing like crazy, what process do you guys use for stainless???

 

Research back purging

 

Sugaring happens when hot stainless steel comes into contact with oxygen. Only way to make sure that it doesn't happen is to have any red hot stainless piece be shielded with argon. That means that both sides of a piece of pipe will need argon to avoid sugaring, AKA, backpurging.

 

I backpurge with this.
http://www.ebay.com/itm/DUAL-HTP-Argon-CO2-Mig-Tig-Flow-meter-Regulator-Welding-Weld-Double-Backpurge-/171091787598?pt=LH_DefaultDomain_0&hash=item27d5dd7f4e

 

What size cups did you use and what flow rates? I flow 30 through a #12 and never have problems unless I try to weld a stupid long bead.

 

purge or solar flux b

 

30 through a #12? the diagram on my machine recommends 14 through a #7. i went to about 17 through a #10 and no back purge. i am just practicing right now, so don't want to waste more argon than i have to since i am just refining my technique...def a different ball game compared to aluminum

 

30 is an awful lot of argon. i run at 17 with a #12 cup and gas lens.

back purging will help with oxidization on the inside of the weld, but not the outside. it is only really needed if you are getting full penetration. adjust your post flow to help with the outside and keep your torch over the weld puddle until the gas stops flowing out of your cup. for longer heavier welds i set it as high as 15-18 seconds. for tack welding, 5 seconds. for 16g like you are practicing on around 12 seconds.

i usually try to use sanitary grade stainless so no cleaning prep is required. if you do need to clean your material, i recommend staying away from any solvents or chemicals to prevent off gasing issues. some people use acetone or varsol. i just use a dedicated stainless steel wire wheel on my bench grinder, or a dedicated stainless steel wire brush if it is required.

aaron

 

Yes, 30cfh through a large #12. It's how I've always done it and it's worked well for me. Like weiRtech said, adjust post flow higher if possible. If not, bump the pedal after you finish your bead to manually extend the post flow time.

I'm a huge advocate of practicing under the same conditions that you'll actually be welding under, even if it costs a few extra dollars.

 

solar flux is a nice solution,

 

bumped up to 22cfh last night and is getting better. going to try to source a #12 cup and gas lense and see if that helps since that appears to be favored both by this group and a local welder i know

 

Check out www.weldingcity.com, good discount shop that ships quick. I've ordered some lens stuff from them before with no problems; it's hard to screw one of these setups up.