By means of macro and micro topography analysis, chemical composition analysis, mechanical property test, and SEM micro topography analysis, the reasons for the fracture of the reducer shaft were analyzed. The main reason; the unreasonable design position of the keyway accelerates the fracture of the reducer shaft.
The fractured reducer axis was cut and sampled, the fracture surface morphology was macroscopically detected, the chemical composition of the reducer shaft was analyzed with a read-only spectrometer, the microstructure of the reducer shaft from the surface to the core was studied with a metallographic microscope, and the microhardness was used. The micro-hardness of the reducer shaft was measured with a meter, and the micro-morphology of the reducer shaft fracture was observed with a SEM scanning electron microscope.
The direct-reading spectral chemical composition analysis results of the reducer shaft material are shown in Table 1. The composition analysis results show that the reducer shaft material is carbon steel and does not contain other alloying elements. According to the general material selection principle of shaft parts, combined with the 45 steel specified by the national standard In the range of chemical composition, except for the silicon element content that is slightly exceeding the standard, other elements meet the requirements of high-quality steel, and it can be determined that the material of the reducer shaft is 45 steel.