Effects of rejuvenation heat treatment on microstructure and creep property of a Ni-based single crystal superalloy

doi:10.1016/j.jmst.2020.05.032

Abstract

Abstract:

Both surface and internal microstructures of a second-generation Ni-based single crystal (SX) superalloy were studied after creep and rejuvenation heat treatment (RHT). It is indicated that the microstructures, such as the dislocation network, the γ phase and the γ' phase, can be recovered to those after the standard heat treatment (SHT). It is found that RHT affected zone (RAZ) formed at the surface is composed of the γ'-free layer, the transition layer and the recrystallization (RX), which are less than 20 μm in depth totally. Such depth of the RAZ doesn’t affect the properties of the superalloy. The morphology of γ' phase at the RAZ is related to the composition of the elements. The average creep life after RHT is close to the average life after SHT. It is concluded that RHT could effectively repair SX parts and increase the total life of the sample after a damage by creep.

Key words: Superalloys, Rejuvenation heat treatment, Microstructure, Creep property

K.J. Tan, X.G. Wang, J.J. Liang, J. Meng, Y.Z. Zhou, X.F. Sun. Effects of rejuvenation heat treatment on microstructure and creep property of a Ni-based single crystal superalloy[J]. J. Mater. Sci. Technol., 2021, 60: 206-215.

Figures/Tables 14

Table 1 Chemical compositions of the second-generation superalloys in this work (wt%).

Cr	Co	Mo + Ta + W	Al	C	B	Re	Hf	Ni
7.0	7.5	13	6.3	0.005	0.004	3	0.15	Bal.

Fig. 1. Creep sample morphology.

Fig. 2. Microstructures of alloys in as-cast (a, b, c) and after SHT (d).

Fig. 3. The creep curve of the alloy (a) and creep interruption curves of samples with two kinds of total strain (b) at 1100 °C/137 MPa.

Table 2 Results of different creep interruption tests (%).

Samples	Total strain	Pre-strain	Elastic strain	Plastic strain
A	0.65	0.37	0.19	0.46
B	0.85	0.17	0.25	0.60

Fig. 4. The interior microstructures of the sample A (a, b) and the sample B (c, d) before RHT.

Fig. 5. Interior microstructures of the sample A (a) and the sample B (b) after RHT.

Fig. 6. The average volume fraction (a), the average size (b) and the distribution (c, d, e) of γ' phase in the samples after SHT and RHT.

Fig. 7. The surface microstructures of the sample A (a, b) and the sample B (c, d) before RHT.

Fig. 8. The surface microstructures of the sample A (a, c, e) and the sample B (b, d, f) after RHT.

Fig. 9. The variation of Al element content with distance.

Table 3 The composition of each region and precipitated phase (wt%).

Location	Ni	Co	Cr	W	Ta	Mo	Re	Al	O
Surface precipitate (H)	21.17	2.53	20.93	22.09	19.63	6.12	1.78	0.05	5.71
γ'-free layer (B)	64.27	7.90	8.68	4.79	10.41	1.17	1.93	0.84	—
Transition layer (D)	68.87	8.92	8.12	5.64	2.26	1.77	2.85	1.59	—
Interior (G)	61.73	10.19	7.78	8.35	5.42	0.92	2.91	2.70	—
Inside precipitate (I)	25.52	2.04	11.01	25.13	20.16	7.20	8.91	0.01	—

Fig. 10. EBSD results of the surface of sample B after RHT.

Fig. 11. The creep life of samples after SHT and after RHT.

References 34

[1]	J. Zhang, L.H. Lou, H. Li, Mater. China 32 (2013) 12-23. DOI URL
[2]	A.D. Cetel, D.N. Duhl, Second-Generation Nickel-Base Single Crystal Superalloy, in: Superalloys, TMS, Warrendale, 1988, pp. 235-244.
[3]	R.J. Cui, Z.H. Huang, K. Guan, J.C. Qin, Y.P. Zhang, Trans. Mater. Heat Treatment 40 (2019) 45-51 (in Chinese).
[4]	K.P.L. Fullagar, R.W. Broomﬁeld, M. Hulands, K. Harris, G.L. Erickson, S.L. Sikkenga, J. Eng, Gas Turbines Power 118 (1996) 380-388. DOI URL
[5]	H.M. Guo, Y.S. Zhao, J. Zheng, J.W. Xu, J. Zhang, Y.S. Luo, J.X. Dong, J. Mater. Eng. 40(2016) 60-67.
[6]	B.K. Lee, W.Y. Song, T.K. Han, C.H. Ye, H.C. Whang, C.Y. Kang, Solid State Phenom. 118(2006) 65-70. DOI URL
[7]	H.M. Tawancy, L.M. Al-Hadhrami, Eng. Failure Anal. 46(2014) 76-91. DOI URL
[8]	Q. Feng, J.Y. Tong, Y.R. Zheng, M.L. Wang, W.J. Wei, H.L. Zhao, X.F. Yuan, X.F. Ding, Mater. China 31 (2012) 21-34.
[9]	M. Abedini, M.R. Jahangiri, P. Karimi, Mater. High Temperatures 36 (2018) 19-26.
[10]	H.I. Kim, H.S. Park, J.M. Koo, C.S. Seok, S.H. Yang, M.Y. Kim, J. Mech. Sci. Technol. 26(2012) 2019-2022. DOI URL
[11]	Y. Zhou, Z. Zhang, Z.H. Zhao, Q.P. Zhong, J. Mater. Eng. Perform. 22(2012) 215-222. DOI URL
[12]	A. James, Mater. Sci. Technol. 17(2001) 481-486. DOI URL
[13]	L. Joseph, L. Paul, N. Douglas, R.D.P. Tiberius, S. Stephanie, Practical Experience with the Development of Superalloy Rejuvenation, in: Proceedings of ASME Turbo Expo 2009, Power for Land, Sea and Air, Orlando, 2009, pp. 1-9.
[14]	P. Wangyao, S. Polsilapa, E. Nisaratanaporn, Acta Metall. Slovaca 11 (2005) 196-206.
[15]	M. Mclean, H.R. Tipler, Assessment of Damage Accumulation and Property Regeneration by Hot Isostatic Pressing and Heat Treatment of Laboratory-Tested and Service Exposed IN738LC, in: Conf. Superalloys, London, 1984, pp. 73-82.
[16]	Z. Yao, C.C. Degnan, M.A.E. Jepson, R.C. Thomson, Mater. Sci. Technol. 29(2013) 775-780. DOI URL
[17]	Z. Yao, C.C. Degnan, M.A.E. Jepson, R.C. Thomson, Metall. Mater. Trans. A 47 (2016) 6330-6338. DOI URL
[18]	Z.X. Shi, S.Z. Liu, J.R. Li, Acta Metall. Sin. (Engl. Lett.) 28(2015) 1278-1285. DOI URL
[19]	J. Zhang, Y.R. Zheng, Q. Feng, Acta Metall. Sin. 52(2016) 717-726 (in Chinese). DOI URL
[20]	W.S. Tang, J.F. Xiao, Y.J. Li, J. Zhang, S.F. Gao, Q. Nan, Acta Metall. Sin. 55(2019) 601-610 (in Chinese). DOI URL
[21]	E. Lvova, J. Mater. Eng. Perform. 16(2007) 254-264. DOI URL
[22]	S.S. Hosseini, S. Nategh, A.A. Ekrami, J. Alloys Compd. 512(2012) 340-350. DOI URL
[23]	S.S. Hosseini, S. Nategh, A.A. Ekrami, Mater. Sci. Technol. 28(2013) 213-219. DOI URL
[24]	C. Monti, A. Giorgetti, L. Tognarelli, F. Mastromatteo, J. Mater. Eng. Perform. 26(2017) 2244-2256. DOI URL
[25]	C. Monti, A. Giorgetti, L. Tognarelli, F. Mastromatteo, J. Mater. Eng. Perform. 27(2018) 2524-2533. DOI URL
[26]	A. Epishin, T. Link, G. Nolze, J. Microscopy 228 (2007) 110-117. DOI URL
[27]	T. Link, A. Epishin, B. Fedelich, Philos. Mag. 89(2009) 1141-1159. DOI URL
[28]	T. Link, A. Epishin, M. Paulisch, T. May, Mater. Sci. Eng. A 528 (2011) 6225-6234. DOI URL
[29]	Z.Y. Song, Q.Y. Sun, L. Xiao, L. Liu, H. Wang, W. Chen, J. Sun, P. Ge, Rare Met. Mater. Eng. 37(2008) 700-703 (in Chinese).
[30]	J.X. Sun, J.L. Liu, L.R. Liu, Y.Z. Zhou, J.G. Li, X.F. Sun, J. Mater. Sci. Technol. 35(2019) 2537-2542. DOI URL
[31]	H.N. Mathur, C. Panwisawas, C.N. Jones, R.C. Reed, C.M.F. Rae, Acta Mater. 129(2017) 112-123. DOI URL
[32]	C.H. Tao, Recrystallization of Directional Solidiﬁcation Superalloy, National Defense Industry Press, Beijing, 2014, pp. 27-31(in Chinese).
[33]	R.B.A. Porter, J. Mater. Sci. 16(1981) 707-713. DOI URL
[34]	R.B.A. Porter, Mater. Sci. Eng. 59(1983) 69-73.