Three interacting circles (metallurgy / mechanical / corrosion)

Tom's framework for thinking about welding-related failures. Each problem can be attacked by shrinking any of the three circles; the metallurgy-only orientation of US welding practice is named as a limitation.

I've never forgotten my three interacting circles — the metallurgy circle, which is microstructure, is one, and there's only so much I can do after I've made my material. Then there's the stress circle. If I relieve the residual stresses or shrink the strain, if I keep it nice and clean — my environment, don't let hydrogen get in, don't let boric acid get up in there — if I keep the system clean by my process or by putting hydrazine in on shutdown to get the oxygen out of the water, I shrink that circle. You can't solve all the problems in the metallurgy circle. Some you have to solve in the mechanical behavior circle, which is residual stresses. Some you have to solve in the corrosion circle, which is the environment. You want to think of it that way. When General Electric had their big stress corrosion cracking problem, they worked on all three circles. One of my problems with most of the philosophy of welding in this country right now is that everything's in the metallurgist's circle. You don't solve it just looking in one area. You attack every area. So that's your question.