Decomposition of Austenite in Fe-25Cr-1N Alloy Produced by Solution Nitriding

Article Preview

Abstract:

The nickel-free austenitic stainless steel produced by solution nitriding (Fe-25%Cr-1%N alloy) was subjected to isothermal heat treatment, and then the microstructure formed through the decomposition of austenite was investigated in terms of the morphology of eutectoid structure and the size of eutectoid block. On the isothermal heat treatment at 873K~1223K for the solution-nitrided steel, the austenite decomposed to eutectoid structure composed of ferrite and Cr2N nitride. This transformation could be completely finished after long time heat treatment in the above temperature range. The nose temperature of T.T.T. curve was around 1173K, and the time to start the eutectoid transformation was only 100~200s. The eutectoid structure was formed mainly along austenite grain boundaries and then grew into the untransformed austenite region. Finally, the austenite was completely decomposed into ferrite and Cr2N nitride. As a result of OIM observation for the specimen after isothermal heat treatment, the eutectoid structure was found to be divided into small-sized ferrite blocks, in which lamellar Cr2N plates were finely distributed. The block size and the mean ferrite path of eutectoid structure were decreased with lowering the heat treatment temperature. In the 873K heat-treated material, these values were estimated at 20 microns and 0.1 microns, respectively.

You might also be interested in these eBooks

Info:

Periodical:

Materials Science Forum (Volumes 539-543)

Pages:

4950-4955

Citation:

Online since:

March 2007

Export:

Price:

Permissions CCC:

Permissions PLS:

Сopyright:

© 2007 Trans Tech Publications Ltd. All Rights Reserved

Share:

Citation:

[1] M. Hasegwa: Handbook of Stainless Steel, THE NIKKAN KOGYO SHIMBUN CO. LTD, Tokyo (1973), p.156.

Google Scholar

[2] Proc. Of 4th Int. Conf. on High Nitrogen Steels, The Iron and Steel Institute of Japan, Tokyo (1995).

Google Scholar

[3] J. Menzel, W. Kirschner and G. Stein: ISIJ Int. Vol. 36 (1996), p.893.

Google Scholar

[4] P. J. Uggowitzer, R. Magdowski and M. O. Speidel: ISIJ Int. Vol. 36 (1996), p.901.

Google Scholar

[5] M.O. Spiedel: Proc. Int. Conf. on Stainless Steels '91, The Iron and Steel Institute of Japan , Tokyo (1991), p.25.

Google Scholar

[6] V.G. Gavriljuk and H. Berns: High Nitrogen Steels-Structure, Properties, Manufacture, Applications, Springer, Berlin (1999), p.135.

Google Scholar

[7] JIS Hand book Tekko, Nihon Kikaku Kyokai, Tokyo (1974), p.99.

Google Scholar

[8] T. Tsuchiyama, T. Fukumaru, M. Egashira and S. Takaki: ISIJ Int. Vol. 44 (2004), p.1121.

Google Scholar

[9] C. M. Garzon and A. P. Tschiptschin: Proc. Int. Conf. on High Nitrogen Steel 2004, GRIPS media GmbH, Bad Harzburg (2004), p.205.

Google Scholar

[10] J. Aghazadeh-Mohandesi, R. Priestner: Metals Technology, Vol. 10 (1983), p.89.

Google Scholar

[11] N, Nakamura and S. Takaki: ISIJ Int. Vol. 36 (1996), p.922.

Google Scholar

[12] T. Tsuchiyama, H. Ito, K. Kataoka and S. Takaki: Metall. Mater. Trans. A Vol. 34 (2003), p.2591.

Google Scholar

[13] H. Berns and S. Siebert: ISIJ Int. Vol. 36 (1996), p.927.

Google Scholar

[14] M. Kajiwara, M. Yamagashira , N. Ono and M. Kikuchi: Abstract of The Japan Society for Heat Treatment, Vol. 23 (1986), p.39.

Google Scholar