Investigation into the failure mechanism of chromia scale thermally grown on an austenitic stainless steel in pure steam

High Temperature Oxidation Behavior of Fe-Cr Steel in Air at 1000-1200 K

“…Meanwhile, the reason for gap formation at the inner/outer oxides interface seems to be the same as oxide cracking and spallation which commonly takes place at the oxide/alloy and oxide/coating interface. Several studies have pointed out that oxide cracking and spallation can occur due to thermal stress arising from a different in thermal expansion between oxide and the underlying materials [3,[5][6][7][8]11,19], grow stress [3,7,8,18] and the formation of other nonadhesive oxide/spinel [7]. During heating and cooling, the thermal stress can enhance the oxide crackingand spalling.…”

“…3(d) we can see that the cracks are formed on the sample surface after exposure at 1200 K for 72 ks. Generally, the cracks can be formed during high temperature oxidation or cooling period [1,3,8]. The structure of oxide scale will be discussed latter based on phase analysis and microstructure characterization.…”

“…Nevertheless, due to a mechanical damage or insufficient amount of Cr content in the alloy, further later on the protective chromia oxide transforms into unprotective oxide scale by forming Fe-rich oxides on the steel surface [6,[8][9][10]. The degradation of chromia oxide can be caused by vaporization of the oxide by forming a volatile species of CrO3 or CrO2(OH)2, especially at high temperature and wet atmosphere [8,9,[11][12][13]. In addition, defects on the oxide scales as cracks and pores can enhance the anion diffusion to the substrate.…”

“…It is well known that iron and alloyed steel usually form three oxides layer consisting of Fe2O3 in the outer layer, FeO on the steel surface and Fe3O4 at the Fe2O3/FeO interface [1][2][3] or two oxides layer consisting of Fe3O4 inner layer and Fe2O3 outer layer, depending on exposure temperature [2,3]. Meanwhile, the ferritic, martensitic and austenitic steels protection against oxidation and corrosion at high temperature are attributed to the formation of a protective Cr2O3 scale through selective oxidation of chromium [4][5][6][7][8]. Accordingly, the sufficient amount of Cr content is needed in  Corresponding author.…”

Steam Oxidation Resistance of Advanced Steels and Ni-Based Alloys at 700 °C for 1000 h

“…[14], and Juana at al. [15] suggesting that the phenomena is related strictly to the breaking mechanism of the oxide scale in pure steam at 700°C. The breakaway of this protective chromia scale formed in steam may be related to the hydrogen permeability and diffusion of Mn to the Cr 2 O 3 .…”