Experimental investigation of fatigue and aging performance of automotive exhaust flexible couplings

In this work, the mechanical strength of automotive exhaust flexible couplings subjected to thermo-mechanical fatigue and corrosion has been investigated. Five different types of flexible coupling have been considered, which is realized by four different metallic materials: three stainless steels (AISI 309, AISI 321, AISI 321 Ti) and a nickel alloy (Incoloy 825). These components have been tested by a specific procedure developed to reproduce the real working conditions of the flexible joints (mechanical stresses, thermal stresses and chemical attacks). The performance of components was compared in terms of variation of both mechanical strength and effect of corrosion, by means of the critical to quality approaches. The fatigue aging process presented in this work reproduced properly the real damage conditions on automotive flexible coupling, and the analysis of the critical to quality results shows that the best components for this application are those made up of Incoloy 825.