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-   -   dc tig mild steel (http://www.allmetalshaping.com/showthread.php?t=18126)

neilb 06-29-2018 04:20 AM

dc tig mild steel
 
i'm having a little trouble with my tig, it welds as though there is no gas, the electrode burns up like it would as if the gas was off. i do have gas flow, pre - during - post welding. doesn't matter which type of electrode i use lanthanated, ceriated, zirconated. i have a gas lens fitted, i recently fitted a gas dryer in the feed line in case of moisture. i'm using and have always used argon/co2 mix, i only weld mild steel. machine is a uni mig 200 a/c

anyone have any ideas? i'm about to change to pure argon just to try it

2lateagain 06-29-2018 04:32 AM

Have you got the polarity around the right way for TIG, positive to earth.


Graham

Bevelhead 06-29-2018 04:58 AM

Dead give away for burning back is incorrect polarity. Also check the lens is not contaminated with spatter

neilb 06-29-2018 05:27 AM

thanks for the quick reply guy's

i can definately say the polarity is correct, i've had this tig about 6 years now and it's only recently it's started to weld like crap lol. i shall check the gas lens and maybe try another. it doesn't get used much to be honest, probably an hour of welding a month at most. so it's hard to pin point when and what, if anything occured when it started going wrong (gas lens fitted, new bottle of gas)

hot rivet 06-29-2018 06:03 AM

If you are tig welding steel with anything other than argon you are going to have problems, CO2 is not an inert gas and that will be part of your problem. From experience tig ceramics will absorb moisture and other chemicals even when they appear dry they can outgas whatever it is they absorbed. Poor storage of you torch may have caused the gas pipe to collapse / get pin holes either restricting gas flow or allowing air in. The other very common problem is bad earth due to cable breakage or clamp making poor contact (arced surfaces)

mastuart 06-29-2018 10:13 AM

You need argon for tig.

Turbo57 06-29-2018 03:06 PM

I think pure argon is better for stainless steel i have more prob when i weld mild steel with that, i dont know what the name is in your country but here it is called Mison and and that is argon with co2, your problem must be something other not the gas:confused:

hot rivet 06-29-2018 04:31 PM

The problem is almost certainly the co2 it breaks down in the arc to form carbon monoxide and oxygen- the oxygen reacts with the tungsten and the steel = porosity and dirty tungsten.

norson 06-29-2018 04:43 PM

Even though you are sure.... double check the polarity. I had the same things happening and that was the problem.

Gareth Davies 06-29-2018 05:12 PM

The gas hose sometimes splits inside the handle, due to the amount of manipulation, and this can allow air to get dragged in. Itís an easy one to check.


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