Fatigue Life of the Repair TIG Welded Hastelloy X Superalloy

• Journal title : Journal of Welding and Joining
• Volume 33, Issue 5,  2015, pp.26-30
• Publisher : The Korean Welding and Joining Society
• DOI : 10.5781/JWJ.2015.33.5.26
Title & Authors
Fatigue Life of the Repair TIG Welded Hastelloy X Superalloy
SIHOTANG, Restu; CHOI, Sang-Kyu; PARK, Sung-Sang; BAEK, Eung-Ryul;

Abstract
Hastelloy X in this study was applied in jet engine F-15 air fighter as shroud to isolate the engine from outer skin. After 15 years operation at elevated temperature the mechanical properties decreased gradually due to the precipitation of continues second phases in the grain boundaries and precipitated inside the grain. The crack happened at the edge of the shroud due to the thermal and mechanical stress from jet engine. Selective TEM analysis found that the grain boundaries consist of $\small{M_{23}C_6}$ carbide, $\small{M_6}$ Ccarbide and small percentage of sigma($\small{{\sigma}}$) phase. Furthermore, it was confirmed the nano size of $\small{{\sigma}}$ and miu ($\small{{\mu}}$) phase inside the grain. In this study, it was investigated the microstructure of the degraded shroud component and HAZ of repair welded shroud. In the HAZ, it was observed the dissolution of the $\small{M_{23}C_6}$ carbides and smaller precipitates, the migration of the undissolved larger $\small{M_{23}C_6}$ carbide and $\small{M_6}$ Ccarbide. It is also observed the liquation due to the simply melt of the segregated precipitates in the grain boundaries. Interestingly, the segregated second phases which simply melt in the grain boundaries more easily happened at higher heat input welding condition. High temperature tensile test was done at $\small{300^{\circ}C}$, $\small{700^{\circ}C}$ and $\small{900^{\circ}C}$. It was obtained that the toughness of welded sample is lower compare to the non-welded sample. The solution heat treatment at $\small{1170^{\circ}C}$ for 5 minutes was suggested to obtain a better mechanical properties of the shroud. The high cycle fatigue number of the repair welded shroud shows a much lower compare to the shroud. In addition, the high cycle fatigue number at room temperature after solution heat treatment was almost double compare to the before solution heat treatment under 420-500MPa stress amplitude. However, the high cycle fatigue number of repaired welded sample was shown a much lower compare to the non- welded shroud and solution treated shroud. One of the main reasons to decrease the tensile strength and the high cycle fatigue properties of the repair welded shroud is the formation of the liquid phase in HAZ.
Keywords
Superalloy;Hastelloy X;Grain boundary liquation;High cycle fatigue test;
Language
English
Cited by
References
1.
E. R. Baek, S. S. Park, R. S. Sihotang and S. K. Choi, Heat treatment of the degraded hastelloy-X for high cycle fatigue properties, Proc. 9th Int. Conf. on Fracture and strength of solid, 91 (2013)

2.
M. J. Ceslak, T. J. Headley and A. D. Romig, Jr, The welding metallurgy of Hastelloy Alloy C-4, C-22 and C-276, Metall. Trans. A, 17A, 1986, 2035-2047

3.
M. J. Perricone and J. N. DuPont, Effect of composition on the solidification behavior of several Ni-Cr-Mo and Fe-Ni-Cr-Mo alloys, Metall. Mater. Trans. A, 37A (2006), 1267-1280

4.
R. B. Leonard, Thermal stability of hastelloy alloy C-276, Corrosion, 25 (1969), 222-228.

5.
C.R. Lee, S.H.Um, S.W. Kim, and C.H.Lee: A study on hot ductility behavior of Ni-based superalloys, Journal of KWJS, 22-2 (2004), 157-166 (in Korean)

6.
Y.S.Kim, Y.G.Choi, C.H.Lim, and J.D.Kim, A study on the abrasive wear properties of the PTA overlay layers using the super alloy powder, Journal of KWJS, 27-3 (2009), 80-84 (in Korean)

7.
M. J. Perricone, J. N. Dupont and M. J. Cieslak, Solidification of hastelloy alloys : an alternative interpretation, Metall. Mater. Trans. A, 34A (2003), 1127-1132.

8.
R. Sihotang, P. Sung-Sang and B.Eung-Ryul, Effect of heat input on microstructure of tungsten inert gas welding used hastelloy-X, Material Research Innovatios. 18 (2014), 1074-1080

9.
O. A. Ojo and M. C. Chaturvedi, Liquation microfissuring in the weld heat-affected zone of an overaged precipitation-hardened nickelbase superalloy, Metall. Mater. Trans. A, 38A (2007), 356-369.

10.
L. O. Osoba, R. K. Sidhu and O. A. Ojo, On preventing HAZ cracking in laser welded DS Rene 80 superalloy, Mater. Sci. Technol., 27 (2011), 897-902.

11.
Z. Tang, J. Li, R. Hu, Y. Liu, and G. Bai, Effect of solution heat treatment on carbide of Ni-Cr-W superalloy, Rare Met. Mater. Eng., 39 (7) (2010), 1157-1161

12.
Z. Yanping, K. Lizhong and X. Xishan, Influence of thermal exposure on the precipitates and mechanical properties of a newly developed Ni-21Cr-17Mo alloy, Mater. Sci. Eng. A, 560 (2013), 611-617

13.
X.Z. Qin, J.T. Guo, C. Yuan, J.S. Hou, L.Z. Zhou and H.Q. Ye, Long-term thermal exposure response of the microstructure and properties of a cast Ni-base superalloy, Mater. Sci. Eng. A, 543 (2012), 121-128

14.
B. Guanghai, L. Jinshan, H. Rui, Z. Tiebang, K. Hongchao and F. Hengzhi, Effect of thermal exposure on the stability of carbides in Ni-Cr-W base superalloy, Mater. Sci. Eng. A, 528 (2011), 2339-2344

15.
N. L. Richards, R. Nakkalil and M. C. Chaturvedi, The influence of electron-beam welding parameters on heataffected-zone microfissuring in Incoloy 903, Metall. Mater. Trans. A, 25A (1994), 1733-1745.