Torsional Fatigue Performance of Induction Hardened 1045 and 10V45 Steels

Microalloying of medium carbon bar steels is a common practice for a number of traditional components; however, use of vanadium microalloyed steels is expanding into applications outside their original designed use as controlled cooled forged and hot rolled products and into heat treated components.  As a result, there is uncertainty regarding the influence of vanadium on the properties of heat treated components, specifically the effect of rapid heat treating such as induction hardening.  In the current study, the torsional fatigue behavior of hot rolled and scan induction hardened 1045 and 10V45 bars are examined at effective case depths of 25, 32, and 44%.  Torsional fatigue tests were conducted at a stress ratio of 0.1 and shear stress amplitudes of 550, 600, and 650 MPa then compared to an empirical model, which accounts for case depth as well as carbon content.   Hardness profiles, microstructures, and fracture behavior are presented and discussed.