Analysis of surface treatment of ASTM A516 Grade 70 using Salt spray method

Abstract

Conversion coating is an effective way to safeguard against corrosion. It is performed on a number of materials inhibiting the surface layer to corrosive attack. In this work surface engineering is carried out on test material ASTM A 516 Grade 70 which is widely used for constructional purposes. During the passivation process samples were given a hot alkaline oxide bath in sodium hydroxide and sodium nitrate. The corrosion resistance was then analyzed using advanced testing procedures. Salt spray test was used as a yard stick in making a comparative analysis of different samples including unpassivated samples, passivated samples and passivated samples with prior surface treatment. Results have shown that mechanical surface treatment improves material life by 3% whereas passivation with prior surface treatment can increase life by 18%.