Experimental investigation on the surface integrity of U71Mn rail via form-milling

Rail form-milling is a typical surface repair technique and can significantly improve wheel/rail contact performance. However, the surface integrity of rail via form-milling has not been systematically studied at present. Therefore, the influence of milling parameters (i.e., milling speed, feed per tooth and radial depth of cut) on the surface integrity of U71Mn rail after form-milling is studied based on rail form-milling test bench. The results show that the surface roughness Ra and Rz decrease by 22.01% and 15.24%, respectively, and the thickness of subsurface plastic deformation layer decreases by 7 μm when milling speed increases by 50%. When the feed rate per tooth increases to 0.5 mm/z, Ra and Rz increase by 53.43% and 28.65%, respectively, and the thickness of subsurface plastic deformation layer increases by 15 μm. Increasing the radial depth of cut to 0.3 mm results in an increase in Ra and Rz of 62.43% and 26.85%, respectively, and an increase in subsurface plastic deformation layer thickness of 13 μm. Increasing milling speed, reducing feed per tooth and radial depth of cut can improve the quality of the micro-morphology. Under the experimental parameters, the microhardness decreases at first and then remains stable with the increase of the distance from the machined surface.