Microhardness variation in the surface layers of the strengthened shafts

The microhardness change regularities in the layers of the shaft working surfaces processed with a ball strengthening tool in the longitudinal and radial directions of the layer are considered. For that purpose, the cylindrical samples of the $40X$ structural steel have been subjected to surface plastic deformity with a strengthening tool at a constant velocity $ V$, with $5$ values of the normal force F, with three longitudinal feeds $S$ ($15$ samples). On the sample surfaces, inclination platforms are processed in those fixed points, measurements of the microhardness $HV$ are carried out. The character of the $ HV$ changes on the mentioned platforms is revealed, and regression equations for determining the $HV$ values by the depth $\Delta h_i$ are obtained. The objective of the study is to select the optimal strengthening technological regimes, which will ensure the required carrying capacity and lifespan of the main elements of the structure.