The high cycle fatigue behavior of niobium micro-alloyed high-Mn austenitic steel with unusual precipitation at 77 K

Abstract

Five high-Mn austenitic steels with different niobium contents are adopted to investigate their fatigue performance at 77 K by a homemade cryogenic device. The results show that although the tensile strength increases with the increase in Nb content, the fatigue performance shows an increasing followed by decreasing trend. Because the density of deformation twins is almost unchanged, so the increase in fatigue performance can be attributed to solution strengthening, grain refinement strengthening and precipitation strengthening. While the decrease can be attributed to the reduced initial microstructure uniformity and precipitates along twin boundaries which reduces the fatigue cracking resistance.