Dissertation
Dissertation > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Steel > Special performance of steels > Stainless steel, acid-resistant steel

A Study of Low Cycle and Thermomechanical Fatigue Behavior of Z2CND18.12N Autenitic Stainless Steel

Author WangLiuBing
Tutor ChenXu
School Tianjin University
Course Chemical Process Equipment
Keywords Z2CND18.12N Thermomechanical fatigue Low cycle fatigue Life Prediction
CLC TG142.71
Type Master's thesis
Year 2010
Downloads 61
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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 .

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