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TIG thick steel to thinner mild steel

Posted: Sun Sep 15, 2019 10:19 am
by fakky
Trying to tig a bracket onto frame of truck. Just tacked right now.

Image

Truck is around 3/8 thick ....... the bracket steel is around 1/8th.

Whats the right way to approach this ? In terms of setup (Amps) .... and preheat or not etc ......
Started out setting to around a split of 150A .... and really it just soaked into the larger metal and blew out the thinner metal.

Re: TIG thick steel to thinner mild steel

Posted: Tue Mar 24, 2020 4:45 pm
by arenjenkins
Really depends on the joint configuration, I'm assuming it's a t type configuration with the 1/8" sticking out from the 3/8" piece?

I would make sure the fit up is really good. The 1/8" piece shouldn't have any gaps. Any place the plate isn't touching is going to make it blow out easily. To me that joint comes down to where you focus the arc and using the filler to cool the puddle where and when you need it. If you can, you can also place some aluminum or copper behind the 1/8" piece to soak up some of the heat.

Re: TIG thick steel to thinner mild steel

Posted: Tue Mar 24, 2020 10:15 pm
by TraditionalToolworks
focus your heat on the thicker 3/8" material or you'll blow out the 1/8" pretty easy...DAMHIKT

Your arc should be on the 3/8" side.

I agree with adding some backer on that 1/8" if you can, to soak up some of the heat.

Re: TIG thick steel to thinner mild steel

Posted: Wed Mar 25, 2020 12:09 am
by bap_
Grinding away that rust before you tacked it up would be a good idea as well.

Like other said using some aluminum backing/heat sync would be a good idea as well. Focus the arc on the 3/8 and wick the puddle up to the thinner material.

You got it!