Method for testing carbide diffusion distance of coated steel

The invention discloses a method for testing the carbide diffusion distance of coated steel. The method comprises the following steps: marking a composite surface based on a target steel metallographic image, performing filtering and noise reduction processing, extracting a contour, and obtaining a composite surface contour comprising an outer contour and an inner contour; and filling the steel base layer outside the outer contour, extracting the contour of the carbide in the composite surface, and finally calculating the carbide diffusion distance by calculating the carbide contour and the outer contour of the composite surface. According to the method, based on a metallographic diagram of the steel-coated material, the boundary of the composite surface and the carbide of the steel-coated material is accurately positioned by using an image recognition algorithm, and then the maximum value from the carbide to the boundary of the composite surface is taken as the diffusion distance of the carbide through a sta