Numerical Analysis of Aerospace Nickel-Based Single-Crystal Superalloy Weldability Part II: Nonequilibrium Solidification Behavior

Abstract:

The thermal metallurgical modeling by coupling of heat transfer model, dendrite selection model, columnar/equiaxed transition (CET) model and nonequilibrium solidification model was further developed to numerically analyze stray grain formation and solidification temperature range on the basis of three criteria of constitutional undercooling, marginal stability of planar front and minimum growth velocity during multicomponent nickel-based single-crystal superalloy weld pool solidification. It is indicated that the primary γ gamma phase microstructure development and solidification cracking susceptibility along the solid/liquid interface are symmetrically distributed throughout the weld pool in (001) and [100] welding configuration. The microstructure development and solidification cracking susceptibility along the solid/liquid interface are asymmetrically distributed in (001) and [110] welding configuration. Appropriate low heat input (low laser power and high welding speed) simultaneously minimizes stray grain formation, grain boundary misorientation and solidification temperature range in the vulnerable [100] dendrite growth region and beneficially maintains single-crystal nature of the material in the [001] epitaxial dendrite growth region to improve the cracking resistance, while high heat input (high laser power and low welding speed) increases the solidification cracking susceptibility to deteriorate weldability and weld integrity. The solidification temperature range in (001) and [110] welding configuration is detrimentally wider than that of (001) and [100] welding configuration due to crystallographic orientation of dendrite growth regardless of heat input. The mechanism of asymmetrical crystallography-dependant solidification cracking because of nonequilibrium solidification behavior is proposed. The elliptical and shallow weld pool shape is less susceptible to solidification cracking for successful crack-free laser welding. Moreover, the promising theoretical predictions agree well with the experiment results. The useful modeling is also applicable to other single-crystal superalloys with similar metallurgical properties during laser welding or laser cladding.

• Periodical: Materials Science Forum (Volume 1018)
• Pages: 33-41
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.1018.33
• Online since: January 2021
• Authors: Zhi Guo Gao*
• Keywords: Crystallographic Orientation, Laser Welding, Nonequilibrium Solidification, Single-Crystal Superalloy, Solidification Cracking, Weldability

References

[1] Weiping Liu, J.N. Dupont. Effects of melt-pool geometry on crystal growth and microstructure development in laser surface-melted superalloy single crystals. Mathematical modeling of single-crystal growth in a melt pool (Part I), Acta Materialia. 52(2004),4833-4847.

DOI: 10.1016/s1359-6454(04)00390-8

[2] Weiping Liu, J.N. Dupont. Effects of substrate crystallographic orientations on crystal growth and microstructure development in laser surface-melted superalloy single crystals. Mathematical modeling of single-crystal growth in a melt pool (Part II), Acta Materialia. 53(2005),1545-1558.

DOI: 10.1016/j.actamat.2004.12.007

[3] D. Dye, O. Hunziker, R.C. Reed. Numerical analysis of the weldability of superalloys, Acta Mater. 49(2001), 683-697.

DOI: 10.1016/s1359-6454(00)00361-x

[4] O.Hunziker, D.Dye, R.C. Reed. On the formation of a centerline grain boundary during fusion welding, Acta Mater. 48(2000),4191-4201.

DOI: 10.1016/s1359-6454(00)00273-1

[5] T.D. Anderson, J.N. Dupont, T.Debroy. Origin of stray grain formation in single-crystal superalloy weld pool from heat transfer and fluid flow modeling, Acta Materialia. 58(2010), 1441-1454.

DOI: 10.1016/j.actamat.2009.10.051

[6] T.D. Anderson, J.N. Dupont, T.Debroy. Stray grain formation in welds of single-crystal Ni-based superalloy CMSX-4, Metallurgical and Materials Transactions A. Vol.41A (2010), 181-193.

DOI: 10.1007/s11661-009-0078-9

[7] M. Rappaz, S.A. David, J.M. Vitek, L.A. Boatner. Analysis of solidification microstructures in Fe-Ni-Cr single-crystal welds, Metallurgical Transactions A. Vol.21A(1990),1767-1782.

DOI: 10.1007/bf02672593

[8] M.Rappaz, S.A. David, J.M. Vitek, L.A. Boatner. Development of microstructure in Fe-15Ni-15Cr single crystal electron beam welds, Metallurgical Transactions A. Vol.20A (1989), 1125-1138.

DOI: 10.1007/bf02650147

[9] M.Rappaz, Ch.a. Gandin. Probabilistic modeling of microstructure formation in solidification processes, Acta Metall.Mater. Vol.41(2) (1993),345-360.

DOI: 10.1016/0956-7151(93)90065-z

[10] J.M. Vitek, S.S. Babu, J.W. Park, S.A. David. Analysis of stray grain formation in single-crystal nickel-based superalloy welds, Proceedings of International Symposium on Superalloys. 2004, 459-465.

DOI: 10.7449/2004/superalloys_2004_459_465

[11] J.W. Park, S.S. Babu, J.M. Vitek, E.A. Kenik, S.A. David. Stray grain formation in single crystal Ni-based superalloy welds, Journal of Applied Physics. Vol.94(6)(2003),4203-4209.

DOI: 10.1063/1.1602950

[12] J.M. Vitek. The effect of welding conditions on stray grain formation in single crystal welds-theoretical analysis, Acta Materialia. 53(2005),53-67.

DOI: 10.1016/j.actamat.2004.08.039

[13] N.Wang, S.Mokadem, M.Rappaz, W.Kurz. Solidification cracking of superalloy single- and bi- crystals, Acta Materialia. 52(2004),3173-3182.

DOI: 10.1016/j.actamat.2004.03.047

[14] R.J. Moat, A.J. Pinkerton, L. Li, P.J. Wither, M.Preuss. Crystallographic texture and microstructure of pulsed diode laser-deposited Waspaloy, Acta Materialia. 57(2009), 1220-1229.

DOI: 10.1016/j.actamat.2008.11.004

[15] M.Gaumann, C.Bezencon, P.Canalis, W. Kurz. Single-crystal laser deposition of superalloys: processing-microstructure maps, Acta Mater. 49(2001),1051-1062.

DOI: 10.1016/s1359-6454(00)00367-0

[16] A.Wagner, B.A. Shollock,M.Mclean. Grain structure development in directional solidification of nickel-based superalloys, Materials Science and Engineering A. 374(2004),270-279.

DOI: 10.1016/j.msea.2004.03.017

[17] X.L. Yang, H.B. Dong, W.Wange, P.D. Lee. Microscale simulation of stray grain formation in investment cast turbine blades, Materials Science and Engineering A. 386(2004),129-139.

DOI: 10.1016/s0921-5093(04)00914-1

[18] A.de. Bussac, Ch.a. Gandin. Prediction of a process window for the investment casting of dendritic single crystals, Materials Science and Engineering A. 237(1997),35-42.

DOI: 10.1016/s0921-5093(97)00081-6

[19] Edward H. Kottcamp. ASM Handbook, Volume 3, Alloy phase diagrams, ASM International, USA,1993,49-155.

[20] Wu Qiong, Li Shusuo, Ma Yue, Gong Shengkai. First principles calculations of alloying element diffusion coefficient in Ni using the five-frequency model, Chin.Phys.B. Vol.21 (10) (2012), 1091021-1-7.

DOI: 10.1088/1674-1056/21/10/109102

[21] J.M. Vitek, S.A. David, S.S. Babu. Optimization of weld conditions and alloy composition for welding single-crystal nickel-based superalloys, Materials Science Forum. Vol.539-543(2007), 3082-3087.

DOI: 10.4028/www.scientific.net/msf.539-543.3082