Flame and Induction Hardening - An Advantageous Alternative to Case Hardening for Large Size Gears?

Surface hardening is an economical and technological alternative to case hardening, especially for larger gear sizes. Due to the high carburization depths required for case hardening with large component dimensions and technological limitations (e. g. furnace size), typical surface hardening processes such as flame or induction hardening show advantages here. In this publication, a flame-spin-hardened variant is compared with an induction-hardened variant using the gap-by-gap method. Both variants have a gear size of mn = 14 mm. A comparison is also made with a case-hardened, shot-peened reference variant of comparable size. In the comparison, the chemical composition, microstructural properties, hardness-depth characteristics and experimental results of the tooth root bending strength tests on the pulsator test rig are presented, comparatively evaluated and discussed. The experimentally determined tooth root load carrying capacities of the two surface-hardened variants are then classified with the reference variant in the state of the art.