Method for measuring thickness of surface film of steel plate

The invention discloses a method for measuring the thickness of a surface film of a steel plate, which comprises the following steps of: 1, adjusting various indexes of a goniometer, driving a z axis of the goniometer, and adjusting a to-be-measured surface of a sample to an axis plane of the goniometer; step 2, selecting a diffraction peak {hkl} of the matrix, measuring diffraction intensity I of the diffraction peak {hkl} at different positions S on the z-axis at a diffraction ray focus and near the diffraction ray focus by taking the zero point of the z-axis as a starting point, and determining a diffraction intensity I-S curve; 3, S corresponding to the peak value of the I-S curve is determined, and therefore the thickness of the to-be-measured sample thin film is measured. According to the method, the thickness of the surface film of the steel plate substrate is measured by using an x-ray diffractometer, an x-ray stress meter and other instruments, the precession function of a z-axis on an objective tabl