NEED SUGGESTIONS OR TIPS ON WELDING .020 STAINLESS STEEl

By rg3psm Date 01-30-2008 01:38

I have almost 3 years welding basically .063 materials and up and i am trying to improve my welding experience and skills and i have hit a snag. I need suggestions or tips on tig welding .020 stainless steel, with as little warping and a small consistent bead as possible without melting through. I am trying to do a lap weld on a will be a rectangular box. The dimensions of the box are approx. 13"h X 11"L X 5"w . I have tried to fabricate this already with some what of a not pretty outcome. Quite a bit of warping and it was tough to keep a small consistent bead. I have clamps and copper bars on to hold the materials together and tacking it about every 1/4 in, using argon and .020 2% thoriated tungsten. I have and only a Lincoln syncrowave 150 tig/stick welder with the only thing you can adjust are the amps ac/dc and on/off. Which i know is probably inadequate for the job but want to know what kind of other fine tune adjustments a machine would need, to see what i would need to invest on. I greatly appreciate any help since i really like this trade and would like to peruse a career in it. Thank you.

By Tommyjoking (****)

Date 01-30-2008 21:39 Edited 02-02-2008 03:34

Hi rg3psm First I want to let you know that this would be tough for a lot of experienced welders....and downright impossible without the right setup. But it can be done without too much fuss, just a bit of patience and preparation.

Your machine: "Lincoln syncrowave 150 tig/stick welder"   If its a Lincoln its not a Syncrowave, if its a Syncrowave its not a Lincoln....Syncrowave is a model of Miller brand. So I am not sure what you are working with but: Your machine will need to be capable of running DCEN (DC negative) at around 10 amps....if you have a foot pedal you will want the range 5-12 amps or so....without a foot pedal this will be tough and you will will have to get the heat perfectly set. "edited for brain failure"

ok now for the welding: Sharp sharp tungsten is your friend. Your tacks are WAY too far apart....tack each end of a joint divide in half and tack again divide distance between those tacks and repeat until they are 1/16-3/32 apart. Use a sacrificial flat screwdriver to help you hold the metal TIGHTLY together on each tack....SS will want to move as soon as you apply heat so you got to hold it down....try to make all your tacks fusion tacks   I.E. don't use filler unless you have too.   Filler: your filler should not be any larger then your base metal...if you are using .032 tig rods this is holding you back....you might want to get some .020 mig wire to use for filler. Keep your filler rods short (10 inches) a floppy 3 ft long rod is not going to help you thread the needle on something this small.....I personally do not use gloves on my filler hand when welding something this fine...that might help you as well (DONT get burned).

Using lap joints will increase your problems with warping. IF you are going to use lap joints use your backing bars directly underneath the weld with two on the weld side clamped as close as you can get them to the joint and still weld it. The backing bar underneath if clamped tightly to your bars above should help with your melt thru...but won't eliminate it. Think about it you have .020 and you only intend to penetrate say .010 with no suckback or penetration with a manual weld??? Thats shooting pretty high.   I personally would do a three piece box (two flat ends and one piece broke into a u shape) and use corner to corner joints. Even better if all these pieces could have an L leg bent at the top (for rigidity). You could use masking tape to hold it together while you get your initial tacks, you can still use a backing bar in those corners or just use a bar inside and one outside on each side of the joint VERY close to the weld clamped together. Making a sandwich of your backing bars inside and out will help minimize your distortion. In the end you could weld it out this way with a gas purge inside and end up with a nice looking fillet inside and a smooth row of laps on the outside of your corners. However you are not going to entirely eliminate warpage/distortion/oilcan you can just minimize it to the point where its acceptable and can be worked out.

Good luck with this and keep us posted on how it works out.

Tommy

By medicinehawk01 (**)

Date 01-30-2008 23:00

That's a really good post, Tommy. I would also add that it might make sense to "back-step" weld. If the box has to be water tight with the lap joint situation you propose, then once it is all tacked up with your chill bars in place, weld 1 inch of metal (fusion only) and then stop. Weld 1 inch, ending the bead on the start of your first 1 inch of weld. Follow this process until you have one side of your box completed. This will help with distortion as it will let you start on a "colder" area as opposed to moving the heat all at once which adds to warping.

By fbrieden (***)

Date 01-30-2008 22:18

Be careful...

By rg3psm Date 01-31-2008 04:55

Tommy,
I would really like to thank you for your advice. I truly appreciate it and the time you took to write all this. It been extremely difficult to actually find someone with some knowledge on this. It might take me a while to let you all know how everything worked for me since i need to acquire some more material. And my mistake it is a Lincoln welder, i had other web pages open researching other welding machines i just got mixed up. If there is way to put pics on here i would gladly also post some up but i will post how things worked out.

Thank you all again,

rg3psm

By Kix

Date 01-31-2008 18:58

Are you using filler rod? If so what size? The smaller the tungsten the better arc stabilization characteristics you will have at these low amperages. When you're running this small a lot of factors come into play to be able to come out with good results. Arc characteristics will be easily effected my flowing to much gas using really low amperage meaning you need a well controlled environment to run lower CFH.
Do a search on how to post pictures and there will be a few threads showing you how.

By Tommyjoking (****)

Date 02-02-2008 03:31

Thx it's no biggie just trying to help a fella out. Medicinehawk is right on with backstepping, it can make a significant difference. There is a HUGE error in my post tho....I was trying to remember range settings I use (machine does not have a readout). Well I am at work and welding some .020,.032 321 pipe and flanges....you should be running a current range of 5-12 amps. Sorry bout that.