Internal Quenching: Ideal Heat Treatment for Difficult to Access Component Sections∗

The heat treatment method Internal Quenching constitutes an alternative method to increase the surface strength of internally loaded high pressure steel components like common rail parts, pipelines, or valves. With the prototypic Internal Quenching device, which was built up at IAM-WK, it is possible to generate hardened surfaces and influence residual stresses in the inner surface of through-drilled parts. This is reached through an austenitisation followed by an internal quenching step, which leads to a martensitic microstructure and compressive residual stresses. Furthermore, it is possible to heat the outer surface by inductive heating during the quenching process which helps to avoid a through hardening of the parts. Due to that various heat treatment strategies can be realized and the residual stresses in the inner surface could be tailored to the load situation.