High-cycle fatigue properties of secondary hardening ultra-high strength steel

High-cycle fatigue properties and fatigue crack growth behavior of high clean secondary hardening ultra-high strength steel (AF1410), which was made by vacuum induction melting followed by vacuum arc remelting (VIM-VAR), have been studied. The experimental results indicate that high clean AF1410 steel has excellent combination of strength and toughness and high resistance on fatigue crack growth. Fatigue strength of smooth specimen (R=0.1, Kt=1) and notch specimen (R=0.1, Kt=3) reaches 1375 MPa and 417 MPa. Fatigue cracks all initiates from specimen surface. Tempering temperature remarkably affects the threshold value of fatigue crack propagation.