Microhardness testing method and system for surface hardness of carbonitrided spline

The invention discloses a microhardness testing method for the surface hardness of a carbonitrided spline. The microhardness testing method comprises the following steps: cutting a metallographic specimen for manufacturing a tooth part along the section of the carbonitrided spline to be detected; establishing a coordinate system and determining a datum line by taking the midpoint of the tooth surface of the spline tooth as an original point O and the contour line at the midpoint of the tooth surface of the spline tooth as an X axis, selecting a plurality of test points on the datum line, and testing and recording the microhardness value of each test point; calculating an average value, a standard deviation and data repeatability; whether the data repeatability is larger than or equal to 5% is judged, when the data repeatability is larger than or equal to 5%, a new test point is selected on the datum line, the microhardness value of the test point is recorded, the data repeatability R is ...