Patent ID: 9587288
Date: 2017-03-07
CPC Classifications: C10M,C21D,C22C,C23C,F16H

Claim:
1. A gear prepared by subjecting a gear precursor comprising iron and, in mass percent: C: 0.15 to 0.45%, Si: 0.05 to 1.0%, Mn: 1.0 to 2.0%, P: 0.05% or less, S: 0.05% or less, Cr: 0.9 to 2%, Al: 0.01 to 0.1%, and N: 0.02% or less, to super-carburizing, quenching, optional tempering, and nitriding, in that order, wherein said gear has a surface-layer part ranging from the surface of the gear to a depth of 20 μm below the surface of the gear that has a steel microstructure comprising a phase of tempered martensite, a phase of tempered bainite, or a composite phase of tempered martensite and tempered bainite, 1 to 10% retained austenite by area percentage, and 5% or more carbide being precipitated by area percentage, the gear also having a nitrogen content of 2.0 to 6.0% in said surface-layer part.