Mig or Tig: which is stronger

[dyn88]

the weakest pat of the joint is the strongest part of the weld. Thats what my instructor used to say many years ago.

[Mike W]

Just weld up some test pieces and stick them in a tensile strength testing machine.

[Paul Seaman]

Masta:
Really the weld strength should be equal, the difference will be in the heat input to achieve a proper weld!

[Masta]

I was referring to more of a Motorsports application, I should have stated that up front. I am a SS Tig welder with my High Pressure vessel ticket and do mostly brewery equipment and installations. We Tig everything. I love Tig and pretty much all out refuse to weld any other way. I'm just trying to settle an internet argument on an automotive board(yes I know arguing on the internet is dumb)

Thanks guys for all your responses, keep em coming.

D.

[arcdawg]

i see that you have gotten some VERY GOOD ADVISE.....(good work guys)

but heres my two pesos........

they oxy weld eaa planes together, they submerge arc(wire) weld bridge beams(at factory)......they tig race car chasis and they stick weld strucutal steel buildings together.....

so in all of these diffrent applacations the weld MUST be strong.......LIVES ARE DEPENDING ON GOOD WELDS........

so diffrent welds for diffrent applacations......

you can get the same tensile strenght wire,rod, filler material for all of your aplacations

dawg

[Masta]

Thanks guys, so by the sounds of it Tig is stronger. Now what would Andy say?
(BTW, it's www.aws.org)

D.

[hankj]

So there's a few opinions. Hard facts? Post the question on the AWS board technical section at www.aws.com and see what you get.

Hank

P.S. I like Paul Seman's opinion the best. Closest to the "hard facts".

[Trent_Combs]

Skill matters!

Tig : inherently stronger, as it is the cleanest weld process available, but somewhat difficult to master

Mig : easier to get a good weld, usually stronger than the base metal

If the weldor is good at it, go Tig. If you want ME to do it, it'll be Mig.

[eric75]

Because of heat loss into the part, a faster/hotter weld will actually have a narrower HAZ.
Slower heating and cooling will reduce internal stresses (caused by thermal expansion), at the sacrifice of some of the material properties (strength caused by work hardening).
So it is a trade off beween larger HAZ or residual stress caused by the weld.

[burninbriar]

I have always liked acetaline torch welding becouse of the slow heat and cool rate.Do you know if there is any truth to acetaline torch welding having a stronger heat afected zone becouse of the slow heat and cool rate.
pete

[Paul Seaman]

Difference of opinion,

Providing proper set up and proper penetration both welds will have the same tensile strength the difference is going to be in the HAZ {heat affected zone} the tig weld will have the smallest HAZ therefore the tig joint will withstand more stress before failure of the surrounding material.

Peace,

[aametalmaster]

D., You are really asking two questions, stronger or better. Depends. Tig is hands down. But it depends if you want stronger or faster. I have seen both welds fail also. We weld 1/2" thick SS pipe with tig. You can put smaller stronger beads with a tig espically on SS...Bob

[Masta]

I'm looking for hard facts, not opinions about what type of welding is stronger and/or better. Mig or Tig. Engineering data would be fine, but some sort of tangible evidence is what I'm looking for. Material would be either M.S. or S.S. approx. 1/8 thick.

Thanks

D.