In view of the tooth breaking phenomenon in high-speed shaft of a wind turbine gearbox of a wind turbine unit

the macroscopic examination

chemical composition analysis

tensile test at room temperature

impact test at room temperature

matrix hardness test

carburizing hardening layer depth test

metallographic analysis

fracture morphology analysis and energy spectrum analysis of the sample were carried out. The results show that

the uneven load existed on the tooth surface of the high speed shaft sample

the depth of the hardened layer did not conform to the requirement of the material sheet

and the shock absorption energy of the substrate at room temperature was at a low level. There were two kinds of damages

namely tooth surface damage and end tooth fracture. The failure mode is fatigue cracking

which is related to the uneven load on the tooth surface and the insufficient depth of hardened layer.