Verification of the estimation methods of strain range in notched specimens made of Mod.9Cr-1Mo steel

Ando, Masanori ; Hirose, Yuichi*; Date, Shingo*; Watanabe, Sota*; Enuma, Yasuhiro*; Kawasaki, Nobuchika 

To verify the methods of estimating strain range for discontinues structures, low cycle fatigue tests were carried out with notched specimens. All the specimens were made of Mod.9Cr-1Mo. Displacement control fatigue tests and thermal fatigue tests were performed by ordinary uni-axial push pull test machine and equipment generating the thermal gradient in the notched plate by induction heating. Elastic and inelastic finite element analysis were also performed to estimate strain range for predicting fatigue life. Then these predictions were compared with the test results. Several methods such as stress reduction locus (SRL) method, simple elastic follow-up (SEF) method, Neuber's law and the procedures employed by elevated temperature design codes were applied. Through these comparisons, the applicability and conservativeness of these strain range estimation methods are discussed.