Process Innovation to Eliminate Cracking Problems in Large Diameter Parts with Nonuniform Wall Thickness

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.