Effects of chemical composition and oxidation temperature on the adhesion of scale in plain carbon steels

Effects of chemical composition and oxidation temperature on blistering and delaminating of scales formed on steels were investigated. The scale blistering occurred for steels with P content above 0.005 mass%. Low carbon steels with 0.01 mass%Si-0.2mass%Mn-0.01 mass%P showed pronounced blistering at 1 223 K. The temperature at which the time to blistering is the shortest, the prominent temperature, decreased with increasing Mn and P contents and deceasing Si content in steels. There was no effect of C, S and sol. Al contents on the such specific temperature. The blistering was promoted by increasing C, Mn and P contents and suppressed by increasing S content at any temperature. The blistering was suppressed at 1 223 K by increasing Si content but promoted at 1 323 K. Sol. AI showed no effect on the acceleration of blistering. The blistering would be correlated to scale texture and segregation of minor elements at the interface between scale and substrate. {111} and {110} oriented crystals in {100} matrix of FeO, that were preferable with increased Si, Mn and P contents, decreased S content and oxidation temperature, accelerated the blistering. The segregated P promoted by increasing P content and decreasing oxidation temperature accelerated the blistering, whereas the segregated Si promoted by increasing Si content and decreasing oxidation temperature suppressed it.