tig welding stainless help.

[steve1989]

hey guys my tig welding on mild steel and alminum is really coming along but recently tried stainless out for the first time.
can some one p,ease give so details about it. ive watched videos on it and stuff but would like to here from some one that is good at it. im welding fillets on 1/8 pieces. using 1/16 ceriated tungsten. any thing better to use? i also have 2 percent lanthenated but havent tried yet. using a gas lend with number 8 cup. im trying to get the weld to look colourful. would love some tips about details. also about tungsten stick out. also i was using 1/16 308 L filler. any thing you know would be much appreciated
cheers guys/girls

[TheGary]

Stainless does not disipate heat very well. So turn down your amperage . set up should be the same as for tig welding steel other than the amperage. On 1/8 stainless I would think you need to set you max amps with the foot pedal all the way down to about 60 amps. I am not used to machines with digital amp readings so I am making an educated guess to what the amps should be. Then try a bead at about the middle of the pedal position then you can roll on or off the amperage as needed. you will need to roll off the foot pedal as the piece heats up. Try to have the amps as low as possible and still run the bead. Stainless will warp very easy so tack everything up good first and do not over heat the metal. If needed walk away and let the piece cool down then go back and finish it. The biggest problem with stainless is too much heat in the piece. If you want the weld to have some color you need less shielding gas so get rid of the gas lens and adjust your stick out till you have the color you want. Personally I would try to have no color difference than the base metal. Then you know you have a good weld with good strength. The filler metal you use depends on your base metal alloy. 308 will work with most alloys but if you have a specific need you need to match the base metal and filler rod for it.

[steve1989]

what do you recomend for amount of gas? and also cup size #?

[TheGary]

what do you recomend for amount of gas? and also cup size #?

In my opinion that is up to the operator. A good welder can compensate for cup size and gas flow to a large extent. I would probably use a cup with about a 3/8 opening and set your gas about the same as you do for steel. The reason I would use a smallish cup is because at low heat settings you are usually working on a small piece and you want to see as good as possible. You can use a larger size if you have the room. The thing to be aware of with gas flow is that it will swirl like an upside down mushroom cloud and when it does it picks up contamination from the air as it swirls back in. The thing you want to do is have it hit the base metal before it swirls . When you up the flow you can use a little more stick out of the tougsten. Only to a point. If you need a lot of stick out then you need to use a gas lens. A gas lens straightens out the gas flow and keeps it from swirling as soon as it would otherwise. You can still go too far but for all intents a gas lens will work for most situations by playing with cup size and pressure used. So you see that with so many combinations of cup size , gas lens or no gas lens, gas pressure changes and stick out there are many ways to skin a cat. You need to find what works best for what you are doing. This sounds hard but it is not really that big of a deal . When I started welding they did not even make gas lenses. I had about 4-5 cup sizes and I was able to do about anything I wanted to. Where a gas lens is the best is if you need a lot of stick out like welding a small dia. tube or pipe on angles like if you were building a frame for a plane or dune buggy or a roll bar. Otherwise it is not needed. sometimes the fat cup that is needed with a gas lens gets in the way of being able to see good.

[zoama]

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