On the Improvement of High-temperature Low-cycle Fatigue Property by Grain-boundary Reaction Precipitates

抄録

The effect of grain-boundary reaction (GBR) on high-temperature low-cycle fatigue life was investigated using an austenitic 21-4N heat-resisting steel at 973K in air. Grain boundary was considerably serrated by the occurrence of GBR during aging. The high-temperature fatigue with symmetrical triangular wave shape. The longest fatigue life was observed in the specimens with about 8% GBR in area fraction. The improvement of fatigue strength resulted from the inhibition of a brittle intergranular fracture by the serrated grain boundary. Therefore, it is important for the improvement of fatigue strength to reduce the extent of GBR to be small and to effectively use the strengthening effect of serrated grain boundary. The fatigue life was less improved by the GBR in the fatigue with asymmetrical triangular wave shape.