Isothermal oxidation behavior of Nb-bearing austenitic cast steels at 950°C

Abstract

The oxidation behaviors of three austenitic cast steels with different morphologies of primary carbides at 950°C in air were investigated using scanning electron microscopy, energy dispersive spectroscopy, and focused ion beam/transmission electron microscopy. Their oxidation kinetics followed a logarithmic law, and the oxidation rate can be significantly decreased as long as a continuous silica layer formed at the scale/substrate interface. When the local Si concentration was inadequate, internal oxidation occurred beneath the oxide scale. The spallation of oxides during cooling can be inhibited with the formation of internal oxidation, owing to the reduced mismatch stress between the oxide scale and the substrate. The “Chinese-script” primary Nb(C,N) was superior to the dispersed primary Nb(C,N) in suppressing the oxidation penetration in the interdendritic region by supplying a high density of quick-diffusion Cr channels. In addition, the innermost and outermost oxidation layers were enriched with Cr, whereas the Cr evaporation in the outermost layer was significant when the water vapor concentration in the environment was high enough. These findings further the understanding regarding the oxidation behavior of austenitic cast steels and will promote the alloy development for exhaust components.

Keywords

austenitic cast steels / isothermal oxidation / primary Nb(C,N) / internal oxidation / Cr depletion

References

[1] Santacreu PO, Faivre L, Acher A. Life prediction approach for stainless steel exhaust manifold. SAE Int. J. Passeng. Cars Mech. Syst., 2012, 5(2): 904.

[2] A.Y. Karnik and M.H. Shelby, Effect of exhaust gas temperature limits on the peak power performance of a turbocharged gasoline engine, J. Eng. Gas Turbines Power, 132(2010), No. 11, art. No. 112801.

[3] Ohmenhäuser F, Schwarz C, Thalmair S, Evirgen HS. Constitutive modeling of the thermo-mechanical fatigue and lifetime behavior of the cast steel 1.4849. Mater. Des., 2014, 64, 631.

[4] Y. Inoue and M. Kikuchi, Present and future trends of stainless steel for automotive exhaust system, Nippon Steel Tech. Rep., 2003, No. 88, p. 62.

[5] Çelik GA, Tzini MIT, Polat Ş, Atapek H, Haidemenopoulos GN. Thermal and microstructural characterization of a novel ductile cast iron modified by aluminum addition. Int. J. Miner. Metall. Mater., 2020, 27(2): 190.

[6] Yan JJ, Huang XF, Huang WG. High-temperature oxidation behavior of 9Cr-5Si-3Al ferritic heat-resistant steel. Int. J. Miner. Metall. Mater., 2020, 27(9): 1244.

[7] Matsumoto K, Tojo M, Jinnai Y, Hayashi N, Ibaraki S. Development of compact and high performance turbocharger for 1050°C exhaust gas. Mitsubishi Heavy Ind. Tech. Rev., 2008, 45(3): 2

[8] Singh H, Sidhu BS, Puri D, Prakash S. Use of plasma spray technology for deposition of high temperature oxidation/corrosion resistant coatings — A review. Mater. Corros., 2007, 58(2): 92.

[9] Francis JM, Jutson JA. The role of silicon in determining the oxidation resistance of an austenitic steel. Mater. Sci. Eng., 1969, 4(2–3): 84.

[10] Bennett MJ, Dearnaley G, Houlton MR, Hawes RWM, Goode PD, Wilkins MA. The influence of surface ion implantation upon the oxidation behaviour of a 20% Cr—25% Ni, niobium stabilized austenitic stainless steel, in carbon dioxide, at 825°C. Corros. Sci., 1980, 20(1): 73.

[11] Lobb RC, Sasse JA, Evans HE. Dependence of oxidation behaviour on silicon content of 20%Cr austenitic steels. Mater. Sci. Technol., 1989, 5(8): 828.

[12] Wild RK. High temperature oxidation of austenitic stainless steel in low oxygen pressure. Corros. Sci., 1977, 17(2): 87.

[13] Basu SN, Yurek GJ. Effect of alloy grain size and silicon content on the oxidation of austenitic Fe-Cr-Ni-Mn-Si alloys in pure O₂. Oxid. Met., 1991, 36(3–4): 281.

[14] Evans HE, Donaldson AT. Silicon and chromium depletion during the long-term oxidation of thin-sectioned austenitic steel. Oxid. Met., 1998, 50(5–6): 457.

[15] Behnamian Y, Mostafaei A, Kohandehghan A, Amirkhiz BS, Serate D, Sun YF, Liu SB, Aghaie E, Zeng YM, Chmielus M, Zheng WY, Guzonas D, Chen WX, Luo JL. A comparative study of oxide scales grown on stainless steel and nickel-based superalloys in ultra-high temperature supercritical water at 800°C. Corros. Sci., 2016, 106, 188.

[16] Z.B. Zheng, S. Wang, J. Long, J. Wang, and K.H. Zheng, Effect of rare earth elements on high temperature oxidation behaviour of austenitic steel, Corros. Sci., 164(2020), art. No. 108359.

[17] C. Gu, R.Z. Liu, C.D. Wang, Y.F. Sun, and S.J. Zhang, Effect of aluminum on microstructure and high-temperature oxidation resistance of austenitic heat-resistant steel, Metals, 10(2020), No. 2, art. No. 176.

[18] Okuyama T, Higashizono T, Luan NHK, Kudo M. Effect of Nb on thermal-shock resistance of austenitic heat resistant cast steel. Mater. Trans., 2020, 61(9): 1711.

[19] Tholence F, Norell M. High temperature corrosion of cast alloys in exhaust environments. II—Cast stainless steels. Oxid. Met., 2008, 69(1–2): 37.

[20] Xu N, Monceau D, Young D, Furtado J. High temperature corrosion of cast heat resisting steels in CO + CO₂ gas mixtures. Corros. Sci., 2008, 50(8): 2398.

[21] Oquab D, Xu N, Monceau D, Young DJ. Subsurface microstructural changes in a cast heat resisting alloy caused by high temperature corrosion. Corros. Sci., 2010, 52(1): 255.

[22] Brady MP, Muralidharan G, Leonard DN, Haynes JA, Weldon RG, England RD. Long-term oxidation of candidate cast iron and stainless steel exhaust system alloys from 650 to 800°C in air with water vapor. Oxid. Met., 2014, 82(5–6): 359.

[23] Yan JB, Gao YM, Liang L, Ye ZZ, Li YF, Chen W, Zhang JJ. Effect of yttrium on the cyclic oxidation behaviour of HP40 heat-resistant steel at 1373 K. Corros. Sci., 2011, 53(1): 329.

[24] Liu YC, Wei WF, Benum L, Oballa M, Gyorffy M, Chen WX. Oxidation behavior of Ni-Cr-Fe-based alloys: Effect of alloy microstructure and silicon content. Oxid. Met., 2010, 73(1–2): 207.

[25] Zhang YH, Li M, Godlewski LA, Zindel JW, Feng Q. Creep behavior at 1273 K (1000 °C) in Nb-bearing austenitic heat-resistant cast steels developed for exhaust component applications. Metall. Mater. Trans. A, 2016, 47(7): 3289.

[26] Zhao HL, Engler-Pinto CC Jr, Zindel J, Godlewski L, Zhang YH, Feng Q, Li M. The effect of metal-carbide morphology on the thermomechanical fatigue (TMF) behavior of cast austenitic alloys for exhaust manifolds. Procedia Eng., 2015, 133, 669.

[27] Zhao HL, Engler-Pinto CC Jr, Tong JY, Godlewski LA, Zindel JW, Li LF, Li M, Feng Q. Mechanical response and dislocation substructure of a cast austenitic steel under low cycle fatigue at elevated temperatures. Mater. Sci. Eng. A, 2017, 703, 422.

[28] Zhang YH, Li M, Godlewski LA, Zindel JW, Feng Q. Effects of N/C ratio on solidification behaviors of novel Nb-bearing austenitic heat-resistant cast steels for exhaust components of gasoline engines. Metall. Mater. Trans. A, 2017, 48(3): 1151.

[29] Ribeiro EAAG, Papaléo R, Guimarães JRC. Microstructure and creep behavior of a niobium alloyed cast heat-resistant 26 pct Cr steel. Metall. Trans. A, 1986, 17(4): 691.

[30] Shingledecker JP, Maziasz PJ, Evans ND, Pollard MJ. Creep behavior of a new cast austenitic alloy. Int. J. Press. Vessels Pip., 2007, 84(1–2): 21.

[31] Onishi T, Nakakubo S, Takeda M. Calculations of internal oxidation rate equations and boundary conditions between internal and external oxidation in silicon containing steels. Mater. Trans., 2010, 51(3): 482.

[32] Wagner C. Reaktionstypen bei der oxydation von legierungen. Z. Elektrochem., 1959, 63(7): 772

[33] Evans HE. Modelling oxide spallation. Mater. High Temp., 1994, 12(2–3): 219.

[34] Lee CC, Tien CL, Sheu WS, Jaing CC. An apparatus for the measurement of internal stress and thermal expansion coefficient of metal oxide films. Rev. Sci. Instrum., 2001, 72(4): 2128.

[35] Qu W, Jian L, Hill JM, Ivey DG. Electrical and microstructural characterization of spinel phases as potential coatings for SOFC metallic interconnects. J. Power Sources, 2006, 153(1): 114.

[36] Saito Y, Maruyama T, Amano T. Adherence of oxide scale formed on Ni-20Cr-1Si alloys with small additions of rare earth elements. Mater. Sci. Eng., 1987, 87, 275.

[37] Fujikawa H, Morimoto T, Nishiyama Y, Newcomb SB. The effects of small additions of yttrium on the high-temperature oxidation resistance of a Si-containing austenitic stainless steel. Oxid. Met., 2003, 59(1–2): 23.

[38] Paúl A, Sánchez R, Montes OM, Odriozola JA. The role of silicon in the reactive-elements effect on the oxidation of conventional austenitic stainless steel. Oxid. Met., 2007, 67(1–2): 87.

[39] Opila EJ, Myers DL, Jacobson NS, Nielsen IMB, Johnson DF, Olminsky JK, Allendorf MD. Theoretical and experimental investigation of the thermochemistry of CrO₂(OH)₂(g). J. Phys. Chem. A, 2007, 111(10): 1971.

[40] Zhang YB, Hu XY, Li CR, Xu WW, Zhao YT. Composition design, phase transitions of a new polycrystalline Ni-Cr-Co-W base superalloy and its isothermal oxidation dynamics behaviors at 1300°C. Mater. Des., 2017, 129, 26.