Shinnosuke FUKUI

Research on the Distinction of Weathering Steel's Evaluated Outward Level of Rust Using Image Processing

The Weathering Steel with its properties of rust is resistant to atmospheric corrosion. Because of a rust layer produced on the steel is compact and stable. The steel using without coating is very economical and superior from the viewpoint of saving materials and energy.
However, the rust on Weathering Steel is influenced by the environment. Therefore it is necessary to inspect and examine the steel after construction. There is the evaluation of outward rust by observing as the method. And the method is evaluating the rust from Level 1 to Level 5. But there are some points at issue of the method. It is that evaluation is changed by subjectivity of a person evaluating the steel.
This research suggested the objective method using image processing as a way out of the issue. It is following method.
1)If the sphere of rust is larger than 1mm2, this is classified from Level 1 to Level 3. Else minute sphere of rust is classified from Level 3 to Level 5.
2)The large sphere of rust is classified between Level 1 and Level 3 from the mean of size and the standard deviation of the size.
3)The minute sphere of rust is classified between Level 3 and Level 5 from the standard deviation of Hue and the mode of Saturation.
Finding of the research is that the evaluation becomes objective by using image processing and this method is able to evaluate at almost the same as the evaluation of outward rust by observing.