Effects of Chemical Composition and Oxidation Temperature on the Adhesion of Scale in Plain Carbon Steels.

Abstract

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 0.01mass%Si-0.2mass%Mn-0.01mass%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. Al 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.

Role of Hematite Formation on Blister Generation during High Temperature Oxidation of Steel

“…In one case, blistering is believed to be caused by stress generated during scale formation. [1][2][3][4] In the other case, gas generation at the scale/steel interface is thought to lead to the formation of blisters. 1,2,5) It was suggested that not only CO and CO2, but also N2, play a role in the blistering phenomenon.…”

Blistering Behavior during Oxide Scale Formation on Steel Surface

“…12). It is reported that blistering is caused by the stress generated during scale formation [1][2][3][4] and also gas release at the scale/ steel interface. 1,2,5,6) The experimental result of blister internal gas measurement supports the latter idea.…”

“…The separated steel surface does not oxidize at this stage, which explains why N 2 gas remains inside the blisters as described above. In this growth process the main driving force of blistering may be scale growth stress [1][2][3][4] or N 2 gas release.…”

“…He also estimated that stress caused by scale formation induced blister generation. Kizu et al 4) investigated the effect of an alloying element on blistering initiation time and this analysis revealed that texture of the scale has effects on the blistering phenomenon. Conversely, in steels containing higher carbon content blistering occur easily.…”

“…One is that blistering is caused by stress generated during scale formation. [1][2][3][4] The other is gas release at the scale/steel interface.…”