The fatigue behaviors of zero-inclusion and commercial 42CrMo steels in the super-long fatigue life regime

In the super-long fatigue life regime the fatigue properties of four high strength 42CrMo steels, two of commercial and two of zero-inclusion grade, respectively, are studied. SEM analysis shows the fatigue crack initiates mostly from non-metallic inclusion for commercial 42CrMo steels, and from the surface matrix for two zero-inclusion steels. The fatigue testing results indicate that, at 2 x 10(6) to 10(9) cycles, it is very difficult to cracking for zero-inclusion steels. (C) 2004 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.