Flexspline Bearing of Harmonic Reducer: Ultimate Load Bearing of 40Cr Steel

40Cr steel is micro-alloyed (with 0.1% Nb addition) to optimize grain boundary strength for manufacturing flexspline bearings in harmonic reducers. Fatigue tests show that it can withstand a torque of 30 N·m with a deformation of <0.01° and a lifespan of 20,000 hours, reducing costs by 50% compared to cobalt-based alloys, contributing to cost reduction in joints of domestic humanoid robots.