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Frontiers of Mechanical Engineering

Front. Mech. Eng.    2018, Vol. 13 Issue (1) : 3-16     https://doi.org/10.1007/s11465-018-0475-0
RESEARCH ARTICLE |
Novel casting processes for single-crystal turbine blades of superalloys
Dexin MA()
Wedge Central South Research Institute, Shenzhen 518045, China
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Abstract

This paper presents a brief review of the current casting techniques for single-crystal (SC) blades, as well as an analysis of the solidification process in complex turbine blades. A series of novel casting methods based on the Bridgman process were presented to illustrate the development in the production of SC blades from superalloys. The grain continuator and the heat conductor techniques were developed to remove geometry-related grain defects. In these techniques, the heat barrier that hinders lateral SC growth from the blade airfoil into the extremities of the platform is minimized. The parallel heating and cooling system was developed to achieve symmetric thermal conditions for SC solidification in blade clusters, thus considerably decreasing the negative shadow effect and its related defects in the current Bridgman process. The dipping and heaving technique, in which thin-shell molds are utilized, was developed to enable the establishment of a high temperature gradient for SC growth and the freckle-free solidification of superalloy castings. Moreover, by applying the targeted cooling and heating technique, a novel concept for the three-dimensional and precise control of SC growth, a proper thermal arrangement may be dynamically established for the microscopic control of SC growth in the critical areas of large industrial gas turbine blades.

Keywords superalloy      investment casting      Bridgman process      directional solidification      single crystal      turbine blade     
Corresponding Authors: Dexin MA   
Just Accepted Date: 30 October 2017   Online First Date: 13 December 2017    Issue Date: 23 January 2018
 Cite this article:   
Dexin MA. Novel casting processes for single-crystal turbine blades of superalloys[J]. Front. Mech. Eng., 2018, 13(1): 3-16.
 URL:  
http://journal.hep.com.cn/fme/EN/10.1007/s11465-018-0475-0
http://journal.hep.com.cn/fme/EN/Y2018/V13/I1/3
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Dexin MA
Fig.1  (a) High-pressure turbine rotor assembled with (b) SC blades
Fig.2  (a) Circular-clustered wax assembly; (b) the corresponding shell mold manufactured for casting SC blades
Fig.3  (a) Schematic of a Bridgman furnace; (b) SC solidification with a grain selector
Fig.4  Schematic of the LMC process [11]
Fig.5  Schematic of the GCC process [18]
Fig.6  (a) Schematic of the SG formation on the blade platform; (b) the corresponding heat barrier and melt undercooling region
Fig.7  (a) Turbine blade of a superalloy with low undercoolability, exhibiting SG formation on the platform; (b) SG growth into the blade root
Fig.8  (a) SC blade fabricated from alloy CMSX-6; (b) the transverse section of the platform showing the three-dimensional growth of SC dendrites; (c) fragmented grain defect in the deeply undercooled edge A
Fig.9  (a) GC technique employed to avoid SG formation; (b) the subgrain boundaries between the bypassed grain and the primary grain from the airfoil
Fig.10  Procedure of shell mold manufacture for HC insertion. (a) Wax model; (b) attachment of HC after the first layer; (c) finished shell mold for dewaxing [29]
Fig.11  Comparison of simulated temperature development (top), typical surface structures (middle) and microstructure in the blade platforms (bottom) between the castings without HC (left: (a1), (a2), (a3)) and those with HC (right: (b1), (b2), (b3)). (a) Without HC; (b) with HC
Fig.12  Sketch of the cylindrical Bridgman furnace currently used for manufacturing SC blade clusters. (a) Transverse section; (b) longitudinal section
Fig.13  Sketch of the PHC system. (a) Transverse section; (b) longitudinal section
Fig.14  Illustration of the D&H process. (a) Dipping the shell mold into the melt bath; (b) mold filling; (c) pulling up the mold to initiate downward solidification
Fig.15  (a) Wall thickness of the shell molds used for the production of turbine blades through the conventional Bridgman process; (b) through the D&H process
Fig.16  (a) D&H experiment with a thin-shell mold to manufacture SC blade of superalloy CMSX-4; (b) as-cast blade; (c) transverse section
Fig.17  Microstructure of CMSX-4 blades produced through the (a) Bridgman and (b) D&H processes
Process G/(K?mm?1) λ1/μm γ/γ′/μm2 γ′/μm Porosity/vol. %
Bridgman 2.2 445.6 1544.2 0.65 0.13
D&H 14.2 299.3 346.9 0.30 0.02
Tab.1  Comparison of the process and structural parameters of the Bridgman and D&H processes
Fig.18  Schematic of TCH in the longitudinal (a) and cross section (b) of a large turbine blade, to precisely control the local SC solidification in the platform and airfoil area respectively.
1 Versnyder F L,  Shank M E. The development of columnar grain and single crystal high temperature materials through directional solidification. Materials Science and Engineering, 1970, 6(4): 213–247
https://doi.org/10.1016/0025-5416(70)90050-9
2 Pratt D C. Industrial casting of superalloys. Materials Science and Technology, 1986, 2(5): 426–435
https://doi.org/10.1179/mst.1986.2.5.426
3 Quested P N, Osgerby  S. Mechanical properties of conventionally cast, directionally solidified and single-crystal superalloys. Materials Science and Technology, 1986, 2(5): 461–475
https://doi.org/10.1179/mst.1986.2.5.461
4 Gebhardt A. Rapid Prototyping. Munich: Carl Hanser Verlag, 2006
5 Feriera J C, Santos  E, Madureira H, et al. Integration of VP/RP/RT/RE/RM for rapid product and process development. Rapid Prototyping Journal, 2006, 12(1): 18–28
https://doi.org/10.1108/13552540610637237
6 Budzik G, Markowski  T, Sobolak M. Hybrid foundry patterns of bevel gears. Archives of Foundry Engineering, 2007, 7(1): 131–134
7 Pattnaik S, Jha  P K, Karunakar  D B. A review of rapid prototyping integrated investment casting processes. Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials Design and Applications, 2014, 228(4): 249–277
https://doi.org/10.1177/1464420713479257
8 Bridgman P W. US Patent, 1793672, 1931-02-24
9 Erickson J S, Owczarski  W A, Curran  P W. Process speeds up directional solidification. Metal Progress, 1971, 99: 58–60
10 Pratt D C. Industrial casting of superalloys. Materials Science and Technology, 1986, 2(5): 426–435
https://doi.org/10.1179/mst.1986.2.5.426
11 Elliott A J, Pollock  T M, Tin  S, et al. Directional solidification of large superalloy castings with radiation and liquid-metal cooling: A comparative assessment. Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science, 2004, 35(10): 3221–3231 
https://doi.org/10.1007/s11661-004-0066-z
12 Tschinkel J G,  Giamei A F,  Kearn B H. US Patent, 3763926, 1973-10-09
13 Giamei A F, Tschinkel  J G. Liquid metal cooling: A new solidification technique. Metallurgical Transactions and Materials Transactions A: Physical Metallurgy and Materials Science, 1976, 7(9): 1427–1434
https://doi.org/10.1007/BF02658829
14 Elliott A J. Directional solidification of large cross-section Ni-base superalloy castings via liquid-metal cooling. Dissertation for the Doctoral Degree. Ann Arbor: The University of Michigan, 2005
15 Liu L, Huang  T, Qu M, et al. High thermal gradient directional solidification and its application in the processing of nickel-based superalloys. Journal of Materials Processing Technology, 2010, 210(1): 159–165 
https://doi.org/10.1016/j.jmatprotec.2009.07.022
16 Zhang J, Luo  L. Directional solidification assisted by liquid metal cooling. Journal of Materials Science and Technology, 2007, 23: 289–300
https://doi.org/10.3321/j.issn:1005-0302.2007.03.001
17 Lohmüller A, Eßer  W, Großmann J, et al. Improved quality and economics of investment castings by liquid metal cooling—The selection of cooling media. In: Proceedings of International Symposium on Superalloys. 2000, 181–188
18 Konter M, Kats  E, Hofmann N. A novel casting process for single crystal gas turbine components. In: Proceedings of International Symposium on Superalloys. 2000, 189–200
19 Wagner A, Shollock  B A, McLean  M. Grain structure development in directional solidification of nickel-base superalloys. Materials Science and Engineering A, 2004, 374(1–2): 270–279
https://doi.org/10.1016/j.msea.2004.03.017
20 Meyer ter Vehn M,  Dedecke D,  Paul U, et al. Undercooling related casting defects in SC turbine blades. In: Proceedings of International Symposium on Superalloys. 1996, 471–479
21 Zhou Y. Formation of stray grains during directional solidification of a nickel-based superalloy. Scripta Materialia, 2011, 65(4): 281–284 
https://doi.org/10.1016/j.scriptamat.2011.04.023
22 Tschinkel J G,  Giamei A F,  Kearn B H. US Patent, 3763926, 1973-10-09
23 Yang X L, Dong  H B, Wang  W,  et al. Microscale simulation of stray grain formation in investment cast turbine blades. Materials Science and Engineering: A, 2004, 386(1–2): 129–139
https://doi.org/10.1016/S0921-5093(04)00914-1
24 Xuan W, Ren  Z, Liu H, et al. Formation of stray grains in directionally solidified Ni-based superalloys with cross-section change regions. Materials Science Forum, 2013, 747–748: 535–539
https://doi.org/10.4028/www.scientific.net/MSF.747-748.535
25 Xuan W, Ren  Z, Li C, et al. Formation of stray grain in cross section area for Ni-based superalloy during directional solidification.  IOP Conference Series: Materials Science and Engineering, 2011, 27: 012035 
https://doi.org/10.1088/1757-899X/27/1/012035
26 Zhang J, Huang  T, Liu L, et al. Advances in solidification characteristics and typical casting defects in nickel-based single crystal superalloys. Acta Metallurgica Sinica, 2015, 51(10): 1163–1178 (in Chinese)
27 Xuan W, Ren  Z, Li C. Experimental evidence of the effect of a high magnetic field on the stray grains formation in cross-section change region for Ni-based superalloy during directional solidification. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, 2015, 46(4): 1461–1466
https://doi.org/10.1007/s11661-015-2787-6
28 Ma D, Wu  Q, Bührig-Polaczek A. Undercoolability of superalloys and solidification defects in single crystal components. Advanced Materials Research, 2011, 278: 417–422 
https://doi.org/10.4028/www.scientific.net/AMR.278.417
29 Ma D, Bührig-Polaczek  A. Application of heat-conductor technique to production of SC turbine blade. Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science, 2009, 40(5): 738–748
https://doi.org/10.1007/s11663-009-9274-7
30 Ma D. Development of single crystal solidification technology for production of superalloy turbine blades. Acta Metallurgica Sinica, 2015, 51(10): 1179–1190 (in Chinese)
31 Ma D, Bührig-Polaczek  A. Avoiding grain defects in single crystal components by application of a heat conductor technique. International Journal of Materials Research, 2009, 100(8): 1145–1151
https://doi.org/10.3139/146.110160
32 Ma D, Bührig-Polaczek  A. Development of heat conductor technique for single crystal components of superalloys. International Journal of Cast Metals Research, 2009, 22(6): 422–429 
https://doi.org/10.1179/174313309X449255
33 Yu J, Xu  Q, Cui K, et al. Numerical simulation of solidification process on single crystal Ni-based superalloy investment castings. Journal of Materials Science and Technology, 2007, 23(1): 47–54
https://doi.org/10.3321/j.issn:1005-0302.2007.01.006
34 Napolitano R E,  Schaefer R J. The convergence-fault mechanism for low-angle boundary formation in single-crystal castings. Journal of Materials Science, 2000, 35(7): 1641–1659
https://doi.org/10.1023/A:1004747612160
35 Ma D, Wu  Q, Bührig-Polaczek A. Investigation on the asymmetry of thermal condition and grain defect formation in customary directional solidification process.  IOP Conference Series: Materials Science and Engineering, 2011, 27: 012037
36 Ma D, Wu  Q, Bührig-Polaczek A. Some new observations on freckle formation in directionally solidified superalloy components. Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science, 2012, 43(2): 344–353
https://doi.org/10.1007/s11663-011-9608-0
37 Ma D, Bührig-Polaczek  A. The influence of surface roughness on freckle formation in directionally solidified superalloy samples. Metallurgical and Materials Transactions. B, Process Metallurgy and Materials Processing Science, 2012, 43(4): 671–677
https://doi.org/10.1007/s11663-012-9691-x
38 Ma D, Bührig-Polaczek  A. The geometry effect of freckle formation in the directionally solidified superalloy CMSX-4. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, 2014, 45(3): 1435–1444
https://doi.org/10.1007/s11661-013-2088-x
39 Ma D, Wang  F, Wu Q, et al. Innovation of casting techniques for single crystal turbine blades of superalloys. In: Proceedings of International Symposium on Superalloys. 2016, 237–246
40 Ma D, Lu  H, Bührig-Polaczek A. Experimental trials of the thin shell casting (TSC) technology for directional solidification.  IOP Conference Series: Materials Science and Engineering, 2011, 27: 012036
41 Wang F, Ma  D, Zhang J, et al. A high thermal gradient directional solidification method for growing superalloy single crystals. Journal of Materials Processing Technology, 2014, 214(12): 3112–3121
https://doi.org/10.1016/j.jmatprotec.2014.07.020
42 Wang F, Ma  D, Bogner S, et al. Comparative investigation of the downward and upward directionally solidified single-crystal blades of superalloy CMSX-4. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, 2016, 47(5): 2376–2386
https://doi.org/10.1007/s11661-016-3415-9
43 Ma D, Grafe  U. Dendrite growth and microsegregation during directional solidification: An analytical model and experimental studies on the superalloys CMSX-4. International Journal of Cast Metals Research, 2000, 13(2): 85–92
https://doi.org/10.1080/13640461.2000.11819391
44 Ma D, Grafe  U. Microsegregation in directionally solidified dendritic-cellular structure of superalloy CMSX-4. Materials Science and Engineering A, 1999, 270(2): 339–342
https://doi.org/10.1016/S0921-5093(99)00208-7
45 Feng Q, Carroll  L J, Pollock  T M. Solidification segregation in Ruthenium-containing nickel-base superalloys. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, 2006, 37(6): 1949–1962
https://doi.org/10.1007/s11661-006-0137-4
46 Caldwell E C, Fela  F J, Fuchs  G E. Segregation of elements in high refractory content single crystal nickel based superalloys. In: Proceedings of International Symposium on Superalloys. 2004. 811–818
47 Caldwell E C, Fela  F J, Fuchs  G E. The segregation of elements in high-refractory-content single-crystal nickel-based superalloys.  Journal of Minerals, Metals and Materials, 2004, 56(9): 44–48 
https://doi.org/10.1007/s11837-004-0200-9
48 Heckl A, Rettig  R, Singer R F. Solidification characteristics and segregation behavior of nickel-base superalloys in dependence on different rhenium and ruthenium contents. Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science, 2010, 41(1): 202–211
https://doi.org/10.1007/s11661-009-0076-y
49 Wang F, Ma  D, Zhang J, et al. Investigation of segregation and density profiles in the mushy zone of CMSX-4 superalloy solidified during downward and upward directional solidification processes. Journal of Alloys and Compounds, 2015, 620: 24–30
https://doi.org/10.1016/j.jallcom.2014.09.103
50 Wang F, Ma  D, Bogner S, et al. Comparative study of the segregation behavior and crystallographic orientation in a nickel-based single-crystal superalloy. Journal of Alloys and Compounds, 2015, 647: 528–532
https://doi.org/10.1016/j.jallcom.2015.04.237
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