Scott,
I strongly disagree with Mr. Granato . It has been my experience on numerous occaisions to see weld test coupons done with MIG break . On one project alone I saw fifty welders have at least one out of four coupons fail ( as in snap in half ). Like I mentioned in a previous email my experiences are supported in the professional literature. There are so many varibles that will affect the outcome the only way to be sure is to do your own testing. That is what industry does. If Mr. Granato is talking about sheet metal then he is correct , it won't make a difference. In heavier thicknesses it most definately does. I have thrity years of welding experience and an investment in welding equipment worth tens of thousands of dollars. I have dedicated MIG welder but the only wire feed type process I will use to build a pressure vessel is Dual Shield Flux Core. MIG welding is fine for body work or building a motorcycle but not a submarine. I would recommend to you to fabricate a guided bend test jig , weld up some test coupons using 516Gr70 and bend in a side bend mode. ( not a root or face mode) .
Dan Lance
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