Effect of Steel Hardenability on Stress Formation in an Induction Hardened Axle Shaft

Previous work reported on the induction hardening process for a 1541 steel axle shaft.  This presentation compares the previous results with the stress formation dynamics in the same shaft made from steels with lower hardenability.  Hardened using a scan heating method and a trailing PAG spray quench, several steels having lower hardenability were modeled using the same heating schedule so that the depth of austenite formation is similar in all cases.  During spray quenching, the hardened case is shallower as steel hardenability is reduced.   This leads to differences in the magnitude of compressive and tensile stresses and their distributions.  In turn, the potential for internal cracking is reduced as the stress transition zone is altered by the thickness of the diffusive phase layer between the martensitic case and the ferrite-pearlite core of the shaft.  The next step is to investigate these effects on the torque carrying ability of the shaft.