Fe-15Mn-10Cr-8Ni-4Si合金の極低サイクル疲労に関する研究

抄録

The extremely low-cycle fatigue (ELCF) behavior and post-fatigue microstructure of a Fe–15Mn–10Cr–8Ni–4Si austenitic alloy were investigated under a strain rate of 0.5% / sec and a maximum strain amplitude of 10% in the axial direction．(1) It was clarified that the steel damper made of Fe-15Mn-10Cr-8Ni-4Si alloy can withstand about 15 swings back even if the structure is distorted by about 10% due to a large earthquake. (2) The _εpa－Nf relationship of the Fe-15Mn-10Cr-8Ni-4Si alloy showed a linear relationship, and the result that Manson-Coffin holds was obtained. (3) Even in the extremely low cycle fatigue test with a strain rate of 0.5% / sec, the test specimen temperature did not exceed 40 °C under all test conditions. Therefore, ε phase was formed in the fatigue test at all test conditions. (4) Many facets and secondary cracks were observed in the fatigue propagation region of the fracture surface. From this, it was inferred that most of the main cracks propagated at the γ/ε interface and the secondary cracks merged. As a result, the fatigue crack could not propagate linearly, and the generation of the secondary crack caused a decrease in the displacement at the tip of the crack when the stress was redistributed, thus extending the fatigue life.