A STUDY ON PITTING INITIATION SITE OF CARBON STEELS
低碳钢点蚀诱发部位的实验研究

Three low carbon steels made by different metallurgical means have been selected. Their susceptibilities to pitting have been compared by means of polarization test, and the pitting characteristic of different inclusions during pitting initiation has been studied with EPMA, and the solution process of inclusions have been investigated with help of agar sealing technique. The results showed that the susceptibility of a boiling steel to pitting initiation was markedly lower than those of killed steels, the pitting susceptibility of a killed steel treated by rare earth was between the boiling steel and another killed steel. The inclusions were the sites most susceptible to pitting initiation. Passivity film at boundary between steel matrix and inclusions was the weakest site, where early pitting corrosion was caused. The composition and morphology of the inclusion will affect the spillage position of the corrosion products.