Corrosion-Fatigue Crack Propagation in Exploited Sucker Rods Made of 20N2M Steel

摘要

We analyze the influence of model stratal water with low acidity on the cyclic crack resistance of 20N2M steel of a sucker rod after operation for 5.5 yr. The state of the metal of a sucker rod head is conventionally regarded as the reference state. We revealed insignificant differences between the basic mechanical properties and the characteristics of cyclic crack-growth resistance of steel in air for different states of the material. However, under the action of corrosive media, the fatigue crack-growth rate for the exploited steel is much higher than for steel in the reference state. This means that the in-service degradation of the rod steel manifests itself mainly in its sensitivity to the action of corrosive media.