High-Temperature Corrosion-Fatigue Behavior of Ductile Cast Irons for Exhaust Manifolds Applications

In the present study, low-cycle fatigue (LCF) tests and oxidation tests in controlled atmospheres are carried out at 800°C on two ductile cast irons SiMo51 and SiMo1000. The LCF tests are carried out in argon and synthetic exhaust gas, whereas oxidation tests are carried out in the latter atmosphere. S-N curves and weight-gain curves are presented. The crack growth mechanisms and oxidation mechanisms are investigated, as well as the synergetic effects. A surprising finding of increased fatigue resistance in oxidizing atmosphere is partly explained.