Fatigue crack growth rate measurement of steam generator tubes based on DCPD method

Abstract

A new testing method based on direct current potential drop(DCPD) and pin loading tension(PLT) method was introduced for evaluating the fatigue crack growth rate of steam generator tubes. In analogy to compact tension(CT) specimens,a testing model was established by using thin-walled tube specimens,and the corresponding mechanical and electrical finite element analyses were made respectively,which determined the data acquisition plan based on DCPD method. Fatigue test was taken on nickel-based alloy 690 used for nuclear power steam generators,and the effects of applied load and temperature were discussed. The result was modeled with the Paris-Erdogan equation and accorded well with this model. Scanning electron microscopy(SEM) examination of the fatigue fracture surfaces revealed transgranular attack,and the transgranular regions of the fatigue fracture surfaces were covered with striation-like features.

Keywords

• nickel chromium iron alloys
• thin-walled tubes
• crack growth rate
• potential drop method