Methods for evaluating metal corrosion

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When metal is corroded, its appearance, weight, dimensions, mechanical strength, and structural composition all change. We can assess the degree of metal corrosion based on these changes in physical and mechanical properties. Since there are various forms of corrosion damage, there are also many methods for assessing the degree of corrosion. We need to select physical and mechanical property indicators that can reflect the degree of corrosion in a relatively accurate and intuitive manner for evaluation. 1. Assessment of surface corrosion is typically done by measuring the change in the weight or thickness of the metal before and after corrosion, in order to determine its average corrosion rate. 1.1 Evaluation based on weight changes: During the corrosion process, the dissolution of metal or the accumulation of corrosion products on its surface can cause the corroded metal to lose weight or gain weight. Based on this change in weight, the degree of corrosion is assessed by determining the change in weight (in grams) per unit area (square meters) of the corroded metal over a unit of time (hours). The corrosion rate can be calculated using the following formula: where K represents the corrosion rate, in grams per square meter per hour; go represents the weight before corrosion, in grams ； g1—weight after corrosion, in grams ； SO – Corroded area, in m2; T – Corrosion time, in hours.