GEAR HAVING EXCELLENT SEIZING RESISTANCE

摘要

This gear has a predetermined chemical composition and has, in a surface-layer part, a texture of tempered martensite and/or tempered bainite and a steel material texture in which retained austenite exists in 1-10% by area percentage and in which a carbide is deposited in at least 5% by area percentage, and the nitrogen content at a depth of 20 μm below the surface is 2.0-6.0%. Thus, a gear that achieves even better seizing resistance in a power transmission part subjected to high rotation and high slippage and using a low-kinematic-viscosity lubricating oil is provided.

主权项

1. A gear having excellent seizing resistance, characterized by comprising C: 0.15 to 0.45% (by mass percent, the same shall apply hereinafter to the chemical compositions), 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, with the remainder consisting of Fe and inevitable impurities, the gear having a surface-layer part that has a steel microstructure including at least one 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, and the gear having a nitrogen content of 2.0 to 6.0% at a depth of 20 μm below a surface of the gear.