Understanding the gear surface enhancement by hard-hobbing via ferritic-martensitic grain analysis

Martensitic phase analysis in hardened gear hobbing (hard-hobbing) is crucial to function-oriented gear manufacturing process. A “weighted deviation factor” has been proposed to integrate machining-induced martensitic alterations into ferritic-martensitic grain analysis. It aimed to assess the martensitic phase using the orientation deviation angle of martensite lattice to the parent austenite to replace the traditional fraction-based assessment. Therefore, the martensitic phase integrity was evaluated with strain-phase hardening to correlate the gear surface function performance. The proposed factor incorporated the martensitic phase integrity as a function of the grain area, local misorientation, and crystallographic deviation, advancing phase-based hardened steel surface modification analysis.