Online measurement of th surface cleanliness of steel strips

The surface cleanliness of steel strip is an important consideration for automotive and drumstock grades. Surface contamination can adversely affect surface treatment. It even strongly modifies radiant exchange in the heat treatment furnaces, affecting metallurgical and mechanical properties. Until now, measurement of surface residues was carried out manually. This method inevitably results in delays in production and can be inconsistent owing to variations in the manual procedures. The typical surface pollution elements are: - Oil: concentration 1 to 30 mg/m 2 after degreasing; up to 400 mg/m 2 otherwise. - Carbon: between 2 and 20 mg/m 2 after annealing. - Iron particles: between 40 and 300 mg/m 2 after rolling; 10 to 20 mg/m 2 after cleaning.