Microstructure and Creep Properties of AISI 316LN Steels with Niobium Additions


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The long-term creep rupture tests have been carried out on three casts of a type AISI 316LN steel at 600 and 650°C. Two of the casts investigated contained additions of 0.1 and 0.3 wt.% of niobium. The growing niobium content strongly reduced the minimum creep rate and prolonged the time to the onset of the tertiary stage of creep and also shortened this stage. The enhanced creep resistance of niobium containing steels is not accompanied by the longer creep life that might have been expected. At both temperatures of creep exposure the niobium-bearing casts displayed an inferior creep ductility. Microstructural investigations revealed that niobium provoked significant grain size refinement and the formation of Z-phase. Particles of this phase were considerably dimensionally stable. Furthermore, niobium accelerated the formation and coarsening of s-phase, h-Laves and M6(C,N). The coarse intergranular particles facilitated the formation of cavities which resulted in intergranular failure mode.



Edited by:

Jaroslav Pokluda




V. Vodárek et al., "Microstructure and Creep Properties of AISI 316LN Steels with Niobium Additions", Materials Science Forum, Vol. 482, pp. 275-278, 2005

Online since:

April 2005




[1] P. Marshall: Austenitic Stainless Steels (Elsevier, London - New York 1984).

[2] J. Sobotka, V. Vodárek and M. Sobotková: Metallurgical Journal, Vol. 47 (1992), 31 (in Czech).

[3] L. Karlsson, A. Henjered, H. -O. Andren and H. Norden: Mat. Sci. Technol., Vol. 1 (1985), p.337.

[4] D.H. Jack and K.H. Jack: JISI, Vol. 209 (1972) p.790.

[5] V. Vodárek, M. Sobotková and J. Sobotka: Microstructural Stability of Creep Resistant Alloys for High Temperature Plant Applications, The Institute of Materials, London 1998, p.69.

[6] V. Vodárek, J. Sobotka, M. Sobotková and J. Sojka: Applications of Stainless Steel 92, Stockholm 1992, p.123.

[7] B. Weiss and R. Stickler: Metallurgical Transactions, Vol. 3A (1972) p.851.

[8] T.M. Williams, D.R. Harries and J. Furnival: JISI, Vol. 210 (1972) p.351.

[9] J. Čadek: Creep kovových materiálů (Academia, Praha 1984).