A Study of Low Cycle and Thermomechanical Fatigue Behavior of Z2CND18.12N Autenitic Stainless Steel
|Course||Chemical Process Equipment|
|Keywords||Z2CND18.12N Thermomechanical fatigue Low cycle fatigue Life Prediction|
Z2CND18.12N belongs to the austenitic stainless steel, its good mechanical properties , corrosion resistance and good heat resistance and are widely used in nuclear power plant design , this paper MTS810 test machine of the material , the total strain control under different temperatures , different amplitudes thermostat fatigue test, and evaluate the impact of temperature and strain amplitude on life , found the material in the cyclic loading experienced a first enhancement, stress saturation and then softening process , its degree of enhancement related strain amplitude . The fatigue design curves on test data and comparison with the ASME curve can be seen very close to room temperature fatigue design curve with the ASME Code , and the overall high temperature SN curves below the ASME curve . Article also studied the thermomechanical fatigue properties of the sample of the material in two sizes in two temperature ranges , different strain , different phase angle of the fatigue life of the material found in the thermomechanical fatigue loading , materials have also gone through the first hardened and then softening process , but the higher the maximum temperature of the cycle , hysteresis asymmetry is more obvious , the longer the cycle to strengthen the process , also completed the cycle maximum temperature low cycle fatigue test to compare , at a high temperature range, it is found that its lifetime value is lower than the conditions of thermomechanical fatigue . The maximum cycle temperature is high , the material will appear dynamic strain aging 550oC under more constant temperature test performance . Heat conditions caused the more obvious average stress , especially in the cyclic temperature range is small , their stretched segment strengthening is more obvious than the compressed section strengthening , so the mean stress is more obvious , and the cycle the higher the maximum temperature , the shorter life expectancy. Through failure sample optical and scanning electron microscope and found that the surface of the crack initiation and crack growth are typical transgranular mode . This paper utilizes several life prediction model test the thermostat fatigue and thermomechanical fatigue life prediction of energy better results in life expectancy .