Heat affected zones

[Weldman]

I am doing a study and wanted to know if any of you guys know if there is a diffrence in the heat affectected zone when you weld a pipe to a I beam using TIG or MIG? I know the process's are completly different as I am a certified welder, basically what I want to do is make a weld on a test piece which is scaled, however the weld would have to be scaled down to 1/8" which is not practical with the MIG setup I have access too, but would like to replicate the weld the MIG gun would make.

Thanks,
Weldman

[enlpck]

Yes, there is a difference. TIG generally puts in more heat than short-arc MIG for a comparable deposit, but not always. Transfer mode and shielding gas have a big effect, and a hotter gas or spray arc can tilt to MIG being hotter. The differences are not minor.


(note that the heat input with TIG can be pretty much unlimited if the travel speed is low enough)

[pulser]

This is kind of a tricky question. To make a given size weld, will require a certain amount of heat input. If the external weld bead dimensions are equal, and the penetration measured in cross section was equal, then the heat input to produce the weld would have to be equal, regardless of being produced by TIG or MIG. Less heat input may lead to lack of fusion, and more heat input could produce more depth of penetration into the base metal, but then the two welds are really not equal.

[weldgault]

Use the Heat input formula and make them the same. JG

[Go1lum]

I would have to think that the total HAZ would be equal if the same heat is used for both processes. But on the otherhand i would have to suspect that the HAZ shape and profiles might be differently shaped with each process.