Characterization of Low-Cycle Fatigue Deformation Behavior at RT/200 °C of FeMnAlC Lightweight Steel for Low-Pressure Turbine Blade

Abstract

In this study, low-cycle fatigueLow-cycle fatigue tests were performed at room temperature/200 °C in total strain range, Δεt = 0.6–2.0% on lightweight steel for low-pressure turbine blade application. The tensile results of Fe–22Mn–8Al–0.9C lightweight steel that show good tensile properties, yield strength and tensile strength were respectively 818 MPa and 1051 MPa, and elongation was 46%. And during low-cycle fatigueLow-cycle fatigue, cyclic softening occurred at room temperature and 100 °C, whereas cyclic hardeningCyclic hardening and Dynamic strain aging occurred at 200 °C in all the investigated total strain ranges, Δεt = 0.6–2.0%. In addition, the serrated flows were observed in the hysteresis loop at 200 °C which is occurred cyclic hardening. However, serrated flows were not observed at RT and 100 °C which is occurred cyclic softening. As a result of TEM observation, the multi-directional slip band and wavy dislocations were observed in the low-cycle fatigueLow-cycle fatigue at RT and 200 °C. However, in the low-cycle fatigue at 200 °C, more frequent wavy dislocations were observed. It seems to be caused by the carbon atoms with a faster diffusion rate effectively fixed dislocations which leads to dynamic strain agingCyclic hardening and Dynamic strain aging and high density of dislocation and resulted in cyclic hardening.