Abstract
The induction hardening process has been widely adopted in the heat treatment industry due to its energy efficiency, process consistency, and clean environment. Compared to traditional furnace heating and liquid quenching processes, induction hardening is more flexible in terms of process adjustment for improved results. The commonly modified process parameters are frequency and power of the inductor, method and timing of power application, and spray quench rate. In this study, a scanning induction hardening process of a generic coupler made of AISI 4150 is investigated by heat treatment process modeling using DANTE. The corner of the non-axisymmetric bore experiences high tensile stresses during the hardening process, which leads to a high possibility of cracking during quenching. The model is used to explain why and how the high tensile stresses are generated. To reduce cracking potential, an innovative process is proposed that reduces the high tensile stresses at the corner, which is demonstrated and validated by modeling. This process modification not only reduces the magnitude of the tensile stress at the corner during induction hardening, but also converts the surface residual stresses at the corner from tension to compression. The residual compression on the bore surface provides improves fatigue performance for the coupler during service.
