Effect of χ Phase on Impact Toughness of 25Cr-7Ni-2Mo-4W Super Duplex Stainless Steel Namgung, Won; Kang, Chang-Yong;
This study was carried out to investigate the precipitation behavior of the phase and the impact toughness of 25%Cr-7%Ni-2%Mo-4%W super duplex stainless steel. The phase was precipitated in the early stage of aging, and with the increasing aging time. However, after reaching a maximum value, the number decreased as a result of the gradual transformation of the phase into the -phase. It was proved that the phase was an intermetallic compound, which represented a lower nickel concentration, higher chromium and molybdenum concentrations, and very higher tungsten concentration compared to the matrix phases. It also showed higher molybdenum and tungsten concentrations than the phase. The decomposition of the ferrite phase into the and phases was retarded by W substitution for Mo. Thus, the number of phases increased. The impact value was decreased by the substitution of W for Mo. The impact toughness rapidly decreased with time when the phase began to precipitate in the initial stage of aging. The impact toughness was, therefore, greatly influenced for the precipitation of the phase.
Effect of χ Phase on Impact Toughness of 25Cr-7Ni-2Mo-4W Super Duplex Stainless Steel, Journal of Ocean Engineering and Technology, 2013, 27, 2, 75
Ahn, Y.S., Kang, J.P., 2000. Effect of Aging Treatments on Microstructure and Impact Properties of Tungsten Substituted 2205 Duplex Stainless Steel. Materials Science and Technology, 16(4), 382-388.
Charles, J., 1994. Structure and Mechanical Properties of Duplex Stainless Steel. Proceedings of 4th Int. Conf. on Duplex Stainless Steels, T.G. Gooch (Ed.), TWI, Cambridge, 1, Paper KI.
Cui, J., Park, I.S., Kang, C.Y., Miyahara, K., 2001. Degradation of Impact Toughness due to Formation R Phase in High Nitrogen 25Cr-7Ni-Mo Super Duplex Stainless Steel. ISIJ Internayional, 41(2), 192-195.
Kang, C.Y., Han, H.S., Lee, S.H., Han, T.S., 2012. Effect of $\chi$ Phase on the Impact Toughness of 25Cr-7Ni-4Mo Super Duplex Stainless Steel. Journal of the Korean Socity for Heat Treatment, 25(2), 74-79.
Kang, C.Y., Kim, J.H., 2011. Effect of $\chi$ Phase Formation on the Mechanical Properties of 25Cr-7Ni-4Mo-0.2N Super Duplex Stainless Steel. Kor. J. Met. Mater., 49(3), 197-202.
Kim, S.C., Bae, D.S., Kang, C.Y., 2009. The Effect of Aging Treatment on the Microstructure and Mechanical Properties of Super Duplex Stainless Steel. Journal of Ocean Engineering and Technology, 23(4), 52-57.
Kondo, K., Ueda, M., Ogawa, K., Okawa, H., Igarashi, M., 1993. Pricipitation Behavior of Sigma -Related Phase in 25% Cr Based Super Duplex Stainless Steel. Proceedings of Inter Conf. On Innovation of Stainless Steels, Florence, Italy, 2, 191.
Okamoto, H., Tsuda, K., Azuma, S., Ueda, M., Ogawa K., Igarashi, M., 1994. Application of Stainless Steel. Proceedings of 4th Int. Conf. on Duplex Stainless Steels, T.G. Gooch (Ed.), TWI, Cambridge, 1, 91.