The Effect of Multiaxial Stress State on Formation of Rafts in CMSX-4 Superalloy during Creep

Abstract:

Article Preview

The effect of multiaxial stress state caused by a notch effect on microstructure degradation of single crystal nickel based superalloy CMSX-4 was studied during creep at a temperature of 950 °C, under constant nominal stress of 120 MPa for 500 and 1000 h. In order to minimize surface oxidation effects on microstructure degradation and notched geometry of specimens, all experiments were performed under protective atmosphere. The geometry of creep specimens was designed with the aim to obtain defined interval of principal stresses, which is sufficiently large to get reliable microstructure response during tensile creep experiments. Flat specimens with “U-type” notch were designed using elastic finite element method (FEM) calculations. Microstructure analysis of the crept specimens showed that notches affect degradation processes of the studied superalloy significantly. FEM elastic-plastic analysis was performed to simulate creep of the notched specimens. Material creep behaviour was integrated into calculations by a subroutine using equations derived from experimentally measured data for cylindrical creep specimens tested at various constant nominal stresses. Magnitude, distribution and orientation of principal stresses resulting from the specimen loading were calculated and their effect on formation of rafts was described.

Info:

Periodical:

Main Theme:

Edited by:

M. Heilmaier

Pages:

222-227

DOI:

10.4028/www.scientific.net/AMR.278.222

Citation:

M. Gebura and J. Lapin, "The Effect of Multiaxial Stress State on Formation of Rafts in CMSX-4 Superalloy during Creep", Advanced Materials Research, Vol. 278, pp. 222-227, 2011

Online since:

July 2011

Export:

[1] J. Lapin, M. Gebura, T. Pelachová, M. Nazmy: Kovove Mater., Vol. 46 (2008), p.313.

[2] A. Baldan: J. Mater. Sci., Vol. 37 (2002), p.2379.

[3] M. Gebura, J. Lapin: Morphological changes of g' in Ni-based superalloy during long-term ageing, In: 17th Int. Conference Metal 2008. Hradec nad Moravicí [CD ROM]. Ostrava: Tanger, (2008).

[4] F.R.N. Nabarro: Metall Mater. Trans A., Vol. 27 (1996), p.513.

[5] A. Ma, D. Dye, R.C. Reed: Acta Mater., Vol. 56 (2008), p.1657.

[6] R.C. Reed, N. Matan, D.C. Cox, M.A. Rist, C.M.F. Rae: Acta Mater., Vol. 47 (1999), p.3367.

[7] M. Gebura, J. Lapin, B Taraba: Microstructure degradation in notched nickel base single crystal superalloy CMSX-4 during creep, In: The 14th International of PhD students' seminar Semdok 2009. Proceedings, Edited by EDIS, Žilina, p.17, (2009).

[8] M. Kamaraj, C. Mayr, M. Kolbe, G. Eggeler: Scripta Mat., Vol. 38 (1998), p.589.

[9] K. Serin, G. Göbenli, G. Eggeler: Mat. Sci. Eng. A, Vol. 387 (2004), p.133.

[10] G. Eggeler, C. Wiesner: J. Strain Analysis for Engineering Design, Vol. 28 (1993), p.13.

[11] J. Lapin, M. Gebura: unpublished results of creep of CMSX-4 superalloy.

In order to see related information, you need to Login.