turbodaddyfrank
- turbodaddyfrank
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New Member
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Joined:Tue Jun 28, 2011 3:58 pm
With both tig and mig welds, if both are done correctly on the same material which is stronger or are they equally as strong and why? What do you think?
- Otto Nobedder
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Weldmonger
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Joined:Thu Jan 06, 2011 11:40 pm
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Location:Near New Orleans
Jody discusses this in several of his articles. All welding methods, when done properly, should produce welds of equal strength (in the same material with the correct filler metal).
"Correctly" means a lot here: Complete penetration, complete fusion of base and filler metals, complete fill, no undercut, porosity, or other flaws, and no overheating.
Differences come in outside the weld, in the HAZ (heat-affected zone), due to the amount of heat input required to perform the weld. Oxy-fuel welding, for example, has a slow, diffuse heat input that affects a broad area of the parent metal, while GMAW accomplishes the same weld in far less time with concentrated heat. On low-carbon steels this is relatively unimportant. On a high-carbon steel you'll affect the hardness, and want as small a HAZ as possible.
Mig and TIG can be comparable in this area as well. TIG has a slower heat input (usually), but a far more concentrated heat zone. TIG also has "local heat control", either through a thumbwheel or foot pedal amp control, or in scratch start, as the parent metal gets hot you can simply move faster.
Several factors determine what process is used, such as production speed vs. required quality, cost vs. required quality, site access vs. required quality. Sensing a theme? Not every weld has to be perfect. It has to be good enough to do it's job within all the constraints of the circumstances.
Wow. That was a bigger ramble than I expected.
Steve
"Correctly" means a lot here: Complete penetration, complete fusion of base and filler metals, complete fill, no undercut, porosity, or other flaws, and no overheating.
Differences come in outside the weld, in the HAZ (heat-affected zone), due to the amount of heat input required to perform the weld. Oxy-fuel welding, for example, has a slow, diffuse heat input that affects a broad area of the parent metal, while GMAW accomplishes the same weld in far less time with concentrated heat. On low-carbon steels this is relatively unimportant. On a high-carbon steel you'll affect the hardness, and want as small a HAZ as possible.
Mig and TIG can be comparable in this area as well. TIG has a slower heat input (usually), but a far more concentrated heat zone. TIG also has "local heat control", either through a thumbwheel or foot pedal amp control, or in scratch start, as the parent metal gets hot you can simply move faster.
Several factors determine what process is used, such as production speed vs. required quality, cost vs. required quality, site access vs. required quality. Sensing a theme? Not every weld has to be perfect. It has to be good enough to do it's job within all the constraints of the circumstances.
Wow. That was a bigger ramble than I expected.
Steve