Low-cycle fatigue strength of notched low-carbon steel materials

Large structures are usually constructed using the conventional low-carbon steel and often contain many kinds of discontinuous cross sections or initial defects. The fatigue cracks commonly initiate at these sites under repeated loadings. So, the estimation of low-cycle fatigue life for the notched components is one of the most important technologies for the structural metals. In this study, the low-cycle fatigue tests were carried out using the smooth round bar specimens and the notched plate ones with the stress concentation factors Kt = 2.43, 3.26 and 4.25. The strains at the notch root were measured over the fatigue tests. The materials used are the hot-rolled low-carbon steel sheets, SM400A and SM490A. On the basis of test results, the method to estimate the strain on the notched structure using Neuber method, Stowell ones and the fatigue life were considered.