Estimation of Maximum Inclusion Size and Fatigue Limit in HSLA-100 Steel

The objective of the current study is to determine the fatigue limit of a clean and high performance material named as HSLA-100 steel, and to compare the obtained fatigue limit with that of theoretically predicted fatigue limit by statistics of extreme value (SEV) method. Also the size of inclusions located at the site of fatigue crack nucleation on the fracture surface of the fatigue test specimens was compared with the results of extreme value distribution of the inclusions as well as with that of analysis of inclusions found on polished specimen. The fatigue cracks were initiated from spherical inclusions in all fatigue test specimens. Analyzing the fatigue results showed that the SEV method can conservatively predict the planar fatigue limit of HSLA-100 steel. Also the largest inclusion size predicted by (SEV) method was larger than that of observed at fatigue crack initiation site as well as metallographic studies of polished specimens.