Fatigue crack propagation study of precipitation hardened steels

The present study deals with the fatigue crack propagation of two different precipitation hardened steels. The two steels differ in the nature of precipitate they bear. The steel having the soft precipitate with coarse grain and the steel having the hard precipitate with fine grain. Instead of having different grain structure and precipitates the two steels have same tensile strength and hardness value. The conventional studies conclude that if two materials have same tensile strength then fatigue properties of two materials will also exhibit same nature. The FEM analysis results obtained concludes that the fatigue property of both steels are not only different but also shows a vice-versa nature for initially small and large crack. The reason for such a behavior is explored using experimental methods, crack growth is monitored and also analytical techniques (Finite element method) were implemented to reach at a final conclusion.