There is at least a major error in that article. I read it superficially and what they describe as fatigue bending is something completely different. Bending a paper clip back and forth causes failure not due to fatigue, but to strain hardening. Fatigue - by definition- occurs before a permanent deformation happens, so the part does not change shape at all. This is a common mistake people who think they know metallurgy are guilty very often. Amen.q