DEVELOPMENT OF SINGLE CRYSTAL SOLIDIFICA- TION TECHNOLOGY FOR PRODUCTION OF SUPERALLOY TURBINE BLADES
MA,Dexin,1,2()
1 Material R&D Center, Dongfang Turbine Co., LTD, Deyang 618000 2 State Key Laboratory of Long-Life High Temperature Materials, Deyang 618000
Cite this article:
MA,Dexin,. DEVELOPMENT OF SINGLE CRYSTAL SOLIDIFICA- TION TECHNOLOGY FOR PRODUCTION OF SUPERALLOY TURBINE BLADES. Acta Metall Sin, 2015, 51(10): 1179-1190.
Based on the analysis of solidification processing in complex turbine blades, a new idea of 3-dimensional and precise control of single crystal (SC) growth was proposed. A series of new techniques were presented,exhibiting the new development in the production of SC blades of superalloys. The heat conductor (HC)technique was developed to minimize the hot barrier effect which hindered the lateral SC growth. This method promotes the successful transition of SC growth from the blade body into the platform extremity prior to the nucleation of stray grains. To achieve symmetric thermal conditions for solidifying the SC blades, the PHC (parallel heating and cooling) system has been employed. With this technique, both sides of a shell mold can be both symmetrically heated in the heating zone as well as cooled in the cooling zone. The negative shadow effect in the current Bridgman process and the related defects are hence removed. With the H&D (dipping and heaving) technique using thin shell, the main problems of the Bridgman process, such as the ineffective radiative heat exchange and the large thermal resistance in thick ceramic molds, can be effectively resolved. This technique enables the establishment of a high temperature gradient at solidification front. By combining targeted cooling and heating technique, a 3-dimensionalcontrol of SC growth in large components can be achieved.
Fig.2 Typical blade geometry (a), schematic illustration of undercooling sequence (b) and SC solidification path in a platform (c)
Fig.3 Transverse section of a CMSX-6 blade platform showing the lateral growth of SC dendrite
Fig.4 Macromorphology of turbine blade of a superalloy having low undercoolability showing stray grains on the platform
Fig.5 Sketch of the grain continuator method (a) and a produced blade with low angle boundaries (LABs) (b)
Fig.6 Principle of heat conductor (HC) technique (a), application of HC in a turbine blade (b) and the structure improvement compared to conventionally produced blade (c) (TL—liquidus isotherm)
Fig.7 Single crystal blade used for power station gas turbine
Fig.8 Sketchs of the cylindrical Bridgman furnace currently used for manufacturing SC blades (TS—solidus isotherm, arrows indicate heat radiation)
(a) top view (b) side view
Fig.9 Sketchs of the new furnace with parallel heating and cooling (PHC) system (Arrows indicate heat radiation)
(a) top view (b) side view
Fig.10 Sketch of combination of targeted cooling and heating technique to precisely control SC solidification
Fig.11 Schematic of the dipping and heaving (D&H) process using thin shell (Vdip—dipping velocity, Vpull—pulling velocity)
(a) dipping the shell mold into the melt bath
(b) mold filling
(c) pulling up the mold to perform a downward solidification
Fig.12 D&H experiment using thin shell to manufacture SC blade of Al alloy in the air (a), as-cast blade with residual shell (b) and macro- and microstructure (right corner) of the SC blade (c)
Fig.13 Schematic of D&H process combined with targeted cooling and heating technique
Fig.14 Setup for D&H process in vacuum (a), a produced SC blade of superalloy CMSX-4 (b) and transverse section of the SC blade showing the fine microstructure (c)
[1]
Versnyder F I, Shank M E. Mater Sci Eng, 1970; A6: 213
[2]
Ericson J S, Owczarski W A, Curran P M. Met Prog, 1971; 109(3): 58
[3]
Liu L. Foundry, 2012; 61: 1273 (刘 林. 铸造, 2012; 61: 1273)
[4]
Fitzgerald T J, Singer R F, Krug P. Eur Pat, EP0775030, 1997
[5]
Elliott A F, Tin S, King W T, Huang S C, Gigliotti M F X, Pollock T M. Metall Mater Trans, 2004; 35A: 3221
[6]
Ma D, Wu Q, Bührig-Polaczek A. Adv Mater Res, 2011; 278: 417
[7]
Meyerter V M, Dedecke D, Paul U, Sahm P R. In: Kissinger R D, Deye D J, Anton D L, Getel A D, Nathal M V, Pollock T M eds., Superalloys 1996, Warrendale: TMS, 1996: 471
[8]
Napolitano R E, Schaefer R J. J Mater Sci, 2000; 35: 1641
[9]
Napolitano R E, Black D R. J Mater Sci, 2004; 39: 7009
[10]
Newell M, Devendra K, Jennings P A, D'Souza N. Mater Sci Eng, 2005; A412: 307
[11]
D'Souza N, Newell M, Devendra K, Jennings P A, Ardakani M G, Shollock B A. Mater Sci Eng, 2005; A413-414: 567
[12]
Giamei A F, Kear B H. Metall Trans, 1970; 1: 2185
[13]
Copley S M, Giamei A F, Johnson S M, Hornbecker M F. Metall Trans, 1970; 1: 2193
[14]
Ma D. Metall Mater Trans, 2004; 35B: 735
[15]
Ma D. J Cryst Growth, 2004; 260: 580
[16]
Ma D, Bührig-Polaczek A. German Patent, DE1020007014744, 2008
[17]
Ma D, Sahm P R, Bührig-Polaczek A. Giesserei, 2009; 96: 124
[18]
Ma D, Bührig-Polaczek A. Int J Mater Res, 2009; 100: 1145
[19]
Ma D, Bührig-Polaczek A. Metall Mater Trans, 2009; 40B: 738
[20]
Ma D, Bührig-Polaczek A. Int Foundry Res, 2010; 62: 32
[21]
Kats L, Konter M. R?sler J, Lubenets V P. German Pat, DE19539770 A1, 1995
[22]
Kats L, Konter M. R?sler J, Lubenets V P. US Pat, 5.921.310, 1995
[23]
Konter M, Kats E, Hofmann N. In: Pollock T M, Kissinger R D, Bowman R R, Green K A, McLean M, Olson S L, Schirra J J eds., Superalloys 2000, Warrendale: TMS, 2000: 189
[24]
Ma D, Wu Q, Bührig-Polaczek A. Mater Sci Eng, 2011; 27: 012037
[25]
Ma D, Wu Q, Bührig-Polaczek A. Metall Mater Trans, 2012; 43B: 344
[26]
Ma D, Bührig-Polaczek A. Metall Mater Trans, 2014; 45A: 1435
[27]
Ma D, Lu H, Bührig-Polaczek A. Mater Sci Eng, 2011; 27: 012036
[28]
Wang F, Ma D, Zhang J, Liu L, Hong J, Bogner S, Bührig-Polaczek A. J Cryst Growth, 2014; 389: 47
