Evaluation of Tensile Properties of Alloy 690TT Steam Generator Tube at Room Temperature and 343℃

This study conducted tensile tests on an Alloy 690TT tube at room temperature (RT) and at 343°C using tube- and ring-type specimens to investigate the stress-strain behavior and tensile properties of a steam generator (SG) tube in the axial and circumferential directions at RT and at the design temperature of a nuclear power plant (NPP). The results of the axial tensile test showed that yield point phenomena appeared at both RT and 343°C, and serrated flow in the stress-strain curve appeared at 343°C. Yield and tensile strengths for both directions were clearly lower at 343°C compared to RT; however, the elongations were approximately the same at both test temperatures. Regardless of the test temperature, the strengths in the circumferential direction were lower by approximately 5-10 % than those in the axial direction. In addition, the test data revealed that the reduction in the yield and tensile strengths of the Alloy 690TT SG tube with the test temperature was more significant than that estimated by the temperature correction factor of ASME Sec.II