Research on Fatigue Behaviors of Nodular Cast Iron QT800 by Laser Shock Processing

The surface of nodular cast iron QT800 was processed with LSP, its micro-structures, residual stress and fatigue test were compared before and after LSP, and the rupture morphologies of fatigue test were analyzed, the effects of LSP on fatigue behavior of QT800 were discussed. The results shown that the compressive residual stress of QT800 by LSP is over 400MPa, and its fatigue life is increased 20% than that in primitive state; the fatigue resource or the sample by LSP is produced near the graphite, compressive residual stress and refined grain effectively delays cracks initiation of the fatigue source, the expansion speed of fatigue cracks is decreased, which increases fatigue life of QT800.