Optimization of sectional dose-response function and determination method of corrosion category for carbon steel

Taking carbon steel as a sample, the single dose-response function in ISO9223: 2012 standard was decomposed into sectional dose-response function corresponding to several corrosion categories. The association rules between atmospheric environmental factors (sulfur dioxide concentration, chloride concentration, wetting time) and corrosion categories were established as confidence coefficients by association rules theory. On this basis, corrosion rates were calculated by weighting the sectional doseresponse function to determine the certain corrosion category. The atmospheric corrosion data of carbon steel from 40 domestic and foreign test sites were used to iudge the corrosion categories by the sectional dose-response function and ISO9223:2012 standard respectively. The results show that the corrosion categories evaluated by the sectional dose-response function were closer to real corrosion categories, compared with ISO9223: 2012 standard. The proposed method is more accurate than ISO9223: 2012 standard to evaluate the corrosion categories of atmospheric corrosivity.