Effect of substrate preset temperature on crystal growth and microstructure formation in laser powder deposition of single-crystal superalloy

doi:10.1016/j.jmst.2018.04.016

Abstract

Abstract:

A successful repair of single-crystal components needs to avoid the stray grain formation and achieves continuous epitaxial growth of columnar dendrites in the repaired zone. In this study, the effect of substrate preset temperature on crystal growth and microstructure formation in laser powder deposition of single-crystal superalloy was studied through an improved mathematical model and corresponding experimental approaches. The results indicated that the variation of substrate preset temperature between -30 °C and +210 °C changes the molten pool morphology little, but obviously affects the columnar-to-equiaxed transition conditions. The preheating of substrate facilitates the stray grain formation and enlarges the primary columnar dendrite arm spacing, while the situation for precooling of substrate is opposite. Under the specific processing conditions, the critical condition for continuous epitaxial growth is that the substrate preset temperature T_sub ≤ +90 °C. When the substrate preset temperature T_sub is below +90 °C, the height ratio of melting depth to total height of the molten pool is larger than that of stray grain, ensuring that stray grains can be completely remelted and the continuous columnar dendrites during the multi-layer laser powder deposition process on (001) surface of single-crystal substrate can be achieved.

Key words: Single-crystal superalloy, Crystal growth, Laser powder deposition

Zhaoyang Liu, Zi Wang. Effect of substrate preset temperature on crystal growth and microstructure formation in laser powder deposition of single-crystal superalloy[J]. J. Mater. Sci. Technol., 2018, 34(11): 2116-2124.

Figures/Tables 11

Fig. 1. Schematic of the coaxial LPD process of SX superalloy with controlling of substrate preset temperature.

Fig. 2. Schematic representation of geometric parameters for describing the deposited bead and associated microstructure formation.

Table 1 Composition of SX superalloy (wt%).

Cr	Co	Mo	W	Ta	Ti	C	Al	Hf	Ni
6.0	10.0	1.5	6.5	6.0	0.4	0.05	6.5	1.0	Bal.

Fig. 3. Comparison of geometrical size and microstructure formation in the transverse section of simulation and experimental deposited bead with the Tsub = (a) -30 °C; (b) +30 °C; (c) +90 °C; (d) +150 °C; (e) +210 °C.

Fig. 4. Variation of (a) width W; (b) melting depth D and (c) height H of molten pool with the change of Tsub from -30 °C to +210 °C.

Fig. 5. Solidification condition in the longitudinal section of the simulation bead with the change of Tsub from -30 °C to +210 °C.

Fig. 6. Variation of height of stray grain Hs with the change of Tsub from -30 °C to +210 °C.

Fig. 7. Observation of the dendritic microstructure perpendicular to the [001] crystal dendrite trunk orientation in deposited bead with the Tsub = (a) -30 °C; (b) +30 °C; (c) +90 °C; (d) +150 °C; (e) +210 °C.

Fig. 8. Variation of PDAS in deposited bead with the change of Tsub from -30 °C to +210 °C.

Fig. 9. Variation of HRm and HRs with the change of Tsub from -30 °C to +210 °C.

Fig. 10. Microstructure and EBSD map in 40-layer deposited bead with (a) Tsub = +210 °C; and (b) Tsub = -30 °C.

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[2]	Shiwei Ci, Jingjing Liang, Jinguo Li, Yizhou Zhou, Xiaofeng Sun. Microstructure and tensile properties of DD32 single crystal Ni-base superalloy repaired by laser metal forming [J]. J. Mater. Sci. Technol., 2020, 45(0): 23-34.
[3]	Jingjing Liang, Yongsheng Liu, Jinguo Li, Yizhou Zhou, Xiaofeng Sun. Epitaxial growth and oxidation behavior of an overlay coating on a Ni-base single-crystal superalloy by laser cladding [J]. J. Mater. Sci. Technol., 2019, 35(2): 344-350.
[4]	Wan Feng, Bai Xiaojun, Song Kaikai, Zheng Jianbang, Lin Xin, Cao Chongde. High pressure floating-zone growth and property characterization of Cr-doped hexagonal YMnO₃ crystals [J]. J. Mater. Sci. Technol., 2017, 33(9): 1061-1066.
[5]	Mohd Anis, M.D. Shirsat, S.S. Hussaini, B. Joshi, G.G. Muley. Effect of Sodium Metasilicate on Structural, Optical, Dielectric and Mechanical Properties of ADP Crystal [J]. J. Mater. Sci. Technol., 2016, 32(1): 62-67.
[6]	S. Sudhahar, M. Krishna Kumar, V. Jayaramakrishnan, R. Muralidharan, R. Mohan Kumar. Effect of Sm⁺ Rare Earth Ion on the Structural, Thermal, Mechanical and Optical Properties of Potassium Hydrogen Phthalate Single Crystals [J]. J. Mater. Sci. Technol., 2014, 30(1): 13-18.
[7]	Hamid Tajizadegan, Majid Jafari, Mehdi Rashidzadeh, Reza Ebrahimi-Kahrizsangi,Omid Torabi. Facile Growth of Porous Hierarchical Structure of ZnO Nanosheets on Alumina Particles via Heterogeneous Precipitation [J]. J. Mater. Sci. Technol., 2013, 29(10): 915-918.
[8]	S. Janarthanan, R. Sugaraj Samuel, S. Selvakumar, Y.C. Rajan, D. Jayaraman. Growth and Characterization of Organic NLO Crystal: β-Naphthol [J]. J Mater Sci Technol, 2011, 27(3): 271-274.
[9]	Yue Zhang,Wei Wei,Yong Liu,Benpeng Zhu,Ping Huang,Ziyu Wang,Zhongpo Zhou,Wufeng Tang,Jing Shi. Effect of Sintering Temperature on the Texturing Behavior of NaCo₂O_4-δ Synthesized by Urea Auto-Combustion Method [J]. J Mater Sci Technol, 2009, 25(06): 742-744.
[10]	C. Justin Raj,S. Krishnan,S. Dinakaran,J. Mary Linet,R. Uthrakumar,R. Robert,S. Jerome Das. Growth, Optical, Mechanical, Dielectric and Theoretical Studies on Potassium Pentaborate Tetrahydrate (KB₅O₈?4H₂O) Single Crystal by Modified Sankaranarayanan-Ramasamy Method [J]. J Mater Sci Technol, 2009, 25(06): 745-748.
[11]	Hongbing Chen,Changyong Zhou,Peizhi Yang,Jinhao Wang. Growth of LaBr₃:Ce³⁺ Single Crystal by Vertical Bridgman Process in Nonvacuum Atmosphere [J]. J Mater Sci Technol, 2009, 25(06): 753-757.
[12]	T.Kishore Kumar, S.Janarthanan, S.M.Ravikumar, S.P, i, M.Vimalan, P.Sagayaraj, D.Prem An. Influence of Metallic Substitutions on the Optical and Mechanical Properties of NLO Benzoyl Glycine Crystals [J]. J Mater Sci Technol, 2008, 24(06): 891-894.
[13]	C.Vesta, R.Uthrakumar, C.Justin Raj, A.Jonie Varjula, J.Mary Linet, S.Jerome Das. Growth, Structural and Microhardness Studies on New Semiorganic Single Crystals of Calcium Para Nitrophenolate Dihydrate [J]. J Mater Sci Technol, 2007, 23(06): 855-859.
[14]	Jiansong WAN, Zhenzhou LU, Zhufeng YUE. Growth of Casting Microcrack and Micropore in Single-crystal Superalloys Analysed by Three-Dimensional Unit Cell [J]. J Mater Sci Technol, 2006, 22(02): 183-189.
[15]	M.J.Bartlett, M.Mocerino, M.I.Ogden, A.Oliveira, G.M.Parkinson, J.K.Pettersen, M.M.Reyhani. Amino Acid Modified Calixarenes as Crystal Growth Modifiers [J]. J Mater Sci Technol, 2005, 21(Supl.1): 1-5.