Abstract
This paper deals with the effects of two types of corrosion resistance coating, CoNiCrAlY and Al chemical vapour deposition (CVD) coating, on the fatigue-creep interaction life of a cast Ni base superalloy René80.
Under a fatigue condition, CoNiCrAlY coating improved the resistance to surface crack initiation, while Al CVD coating reduced the number of cycles to surface crack initiation. However, the surface crack propagation rates of both the coated and non-coated specimens were about the same value. Under a fatigue-creep interaction condition, the number of cycles to surface crack initiation of the coated specimen increased in comparison with the non-coated specimen. The surface crack propagation rate of the coated specimen increased in comparison with the non-coated specimens.
It was found that the fatigue life of the coated specimen was affected by the oxidation of the specimen surface and the properties of the coating meterial. The life under fatigue creep interaction was affected by the failure mechanism (intergranular cracking) of the base metal René80 rather than the oxidation and the properties of the coating material.
