Oxidation behavior of AISI 321, AISI 316, and AISI 409 stainless steels: Kinetic, thermodynamic, and diffusion studies
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Seyedeh Sogol Pelaseyed and Mitra Attariana) Department of Materials Science and Engineering, Sharif University of Technology, Tehran 11365, Iran; and Razi Metallurgical Research Center (RMRC), Tehran 37515, Iran
Reza Shokrallahzadeh Iran Power Plant Project Management MAPNA, Tehran, Iran (Received 3 September 2015; accepted 17 March 2016)
The oxidation behavior of three types of stainless steels, namely AISI 321, AISI 316, and AISI 409, was compared. In all stainless steels, oxide layers were formed and their masses and thicknesses increased with oxidation time. Among them, AISI 409 ferritic stainless steel demonstrated higher oxidation rate. According to the kinetical oxidation behavior of them at elevated temperatures, the oxidation mechanism was determined. Among them, the AISI 409 ferritic stainless steel showed the lowest and AISI 321 austenitic stainless steel demonstrated the highest oxidation resistance. Based on the experimental results, it was suggested that the kinetic of oxide growth in stainless steels was followed by a parabolic relationship. In all cases, a well-known Cr-rich internal oxidation zone (IOZ) was observed. The formation of IOZ was suggested by the Gibbs free energy expression and confirmed by following up the formed oxide layers at different holding times. Furthermore, the formation of thicker oxide layers in ferritic stainless steel was explained by using solid-state diffusion relations and supported by quasi-steady-state approximation of Fick’s first law.
I. INTRODUCTION
Undoubtedly, steels are dominating industrial materials. Among them, stainless steels with notable mechanical properties and corrosion resistance are completely essential for using in tools, structural, and energy applications. These are due to the presence of alloying elements such as chromium and nickel, which make stainless steels quite distinct and superior from other grades of steels, especially at the harsh atmosphere and elevated temperature.1,2 Among the different grades of stainless steels, austenitic stainless steels such as AISI 321 and AISI 316 with high contents of Cr and Ni are wildly used in the industries at intermediate temperature (923–1073 K).3 Recently, ferritic stainless steels like AISI 409 by offering lower costs than austenitic grades, due the absence of nickel element and offering lower expansion coefficient than austenitic steels, as a great advantage when temperature cycling resistance is needed, have been developed.4–6 The presence of heavy oxidation at the elevated temperature can cause degradation of the materials and Contributing Editor: Edson Roberto Leite a) Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/jmr.2016.141
excessive metal temperature during the operation. It is because of the lower thermal conductivity of oxides in comparison to the steels and may cause creep damage and structural degradation.2,7 In addition to the temperature, there are some other factors, which are effective on the oxidation behavior of steels. For example, che
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