TIG welding a fuel rail on mild steel

[steelstitch]

I'm trying to TIG weld a small fuel rail to some 3mm mild steel. I'm using a 1/8 gray electrode and E71T-2 filler, but the puddle is acting up and I'm getting a lot of burn-through because of too much heat. Should I try preheating the steel? Or would it be better to switch to a different filler? Or maybe just use MIG welding instead? Any tips would be really helpful

 

[GGoldfinch66]

I had a similar job last year, welding a fuel rail bracket to 3mm mild steel for a boat. I used TIG with a 1/8" gray tungsten too, but E71T-2 is made for MIG welding, not TIG. I switched to ER70S-2 or ER70S-6 rods, and it worked much better.

Are you using pulse mode or short welds to keep the heat down? That helped me stop burn-through. Also, what kind of joint are you welding, is it lap, butt, or fillet? That affects how much heat you need.

 

[Dillydally]

You're running way too hot for that thin stuff. Preheating won't help and if anything it'll make it worse, try dropping to a smaller tungsten and filler, back off the amps, and you'll have way more control. MIG would definitely be easier if you're not set on TIG

 

[StillAlive]

I'm trying to TIG weld a small fuel rail to some 3mm mild steel. I'm using a 1/8 gray electrode and E71T-2 filler, but the puddle is acting up and I'm getting a lot of burn-through because of too much heat. Should I try preheating the steel? Or would it be better to switch to a different filler? Or maybe just use MIG welding instead? Any tips would be really helpful

the problem here's the E71T-2 filler. like @GGoldfinch66 said, that's actually a gas shielded flux cored wire meant for MIG welding, not TIG. The flux inside is reacting with your TIG arc and making the puddle act all weird, which is why you're getting so much trouble.
The correct filler for TIG welding mild steel is something like ER70S-2 or ER70S-6. Once you get the right filler, your puddle will be a hundred times more manageable

 

[Imperial_Alen]

Don't overcomplicate it. No preheat needed. Just swap to the right filler rod (ER70S-2 is cheap and works on mild steel) and drop down to a smaller tungsten... 3/32 works fine. MIG would be faster, but you'll get more spatter to clean up.

 

[whimp parrot]

That's a classic TIG welding problem when working with a significant difference in metal thickness. The issues you're describing like the puddle acting up, burn-through, and too much hea... They all point to the same root cause: you are putting too much heat into the thinner material. In short, your primary problem is using the wrong filler material. Get the right TIG filler rod, and then practice your technique by focusing your arc on the thicker metal and moving quickly. Do not preheat. Stick with TIG, as it is the best process for this type of detailed work.