Investment casting of nozzle guide vanes from nickel-based superalloys: part I – thermal calibration and porosity prediction
Investment casting is the only commercially used technique for fabrication of nozzle guide vanes (NGVs), which are one of the most important structural parts of gas turbines. Manufacturing of NGVs has always been a challenging task due to their complex shape. This work focuses on development of a simulation tool for investment casting of a new generation NGV from MAR-M247 Ni-based superalloy. A thermal model is developed to predict thermal history during investment casting. Experimental casting trials of the NGV are carried out and the thermal history of metal, mold, and insulation wrap is recorded. Inverse modeling of the casting trials is used to define accurately some thermophysical parameters and boundary conditions of the thermal model. Based on the validated thermal model, another model is developed to predict porosity in the as-cast NGVs. The porosity predictions are in good agreement with the experimental results in the as-cast NGVs. The advantages and shortcomings of the developed modeling tool are discussed.
KeywordsNi-based superalloys Investment casting Nozzle guide vanes Thermal model Thermal history Porosity
This investigation was carried out in frame of the VANCAST project (EU, FP7, ERA-NET MATERA+). SM and IS acknowledge gratefully the Spanish Ministry of Economy and Competitiveness for financial support through the Ramon y Cajal fellowships. Prof. A. Zryd (Maxwell Technologies SA) and Dr. A. Faes (CSEM SA) are greatly acknowledged for the inverse simulations of experimental casting trials of easy geometry parts as those results constituted the seed for experimental work which had led to this manuscript.
- 1.Razak AMY: Industrial gas turbines: performance and operability. Woodhead Publishing Limited, Cambridge, UK; 2007.Google Scholar
- 6.Stefanescu DM: Science and Engineering of Casting Solidification. 2nd edition. Springer Science + Business Media, New York, NY, USA; 2009.Google Scholar
- 7.Piwonka TS, Flemings MC: Pore formation in solidification. Trans AIME 1966, 236(8):1157–1165.Google Scholar
- 8.Pellini WS: Factors which determine riser adequacy and feeding range. AFS Transactions 1953, 61: 61–80.Google Scholar
- 9.Niyama E, Uchida T, Morikawa M, Saito S: Predicting shrinkage in large steel castings from temperature gradient calculations. AFS Int Cast Met J 1981, 6(2):16–22.Google Scholar
- 13.Lee PD, Chirazi A, Atwood RC, Wang W: Multiscale modeling of solidification microstructures, including microsegregation and microporosity, in an Al-Si-Cu alloy. Mater Sci Eng A 2004, 365: 57–65. doi:10.1016/j.msea.2003.09.007 doi:10.1016/j.msea.2003.09.007 10.1016/j.msea.2003.09.007CrossRefGoogle Scholar
- 15.Pequet C, Rappaz M, Gremaud M: Modeling of microporosity, macroporosity, and pipe-shrinkage formation during the solidification of alloys using a mushy-zone refinement method: applications to aluminum alloys. Metall Mater Trans A 2002, 33: 2095–2106. doi:10.1007/s11661–002–0041–5CrossRefGoogle Scholar
- 17.Couturier G, Rappaz M: Modeling of porosity formation in multicomponent alloys in the presence of several dissolved gases and volatile solute elements. TMS Annual Meeting, San Antonio, TX, USA; 2006.Google Scholar
- 20.Overfelt RA, Sahai V, Ko YK, Berry JT: Porosity in cast equiaxed alloy 718. In Proceedings of the TMS Meeting Edited by: Loria EA. 1994, 189.Google Scholar
- 21.Monastyrskiy VP: Modeling of porosity formation in Ni-based superalloys. In Proceedings of the 8th Pacific Rim International Conference on Modeling of Casting and Solidification Process Edited by: Choi JK. 2010, 89.Google Scholar
- 23.Calba L, Lefebvre D: Modeling the investment casting process. ESI-GROUP Resource Center, Paris; 2008.Google Scholar
- 24.Harris K, Erickson GL, Schwer RE: MAR-M247 derivations—CM247 LC DS alloy, CMSX single crystal alloys, properties and performance. In Proceedings of the 5th International Symposium on Superalloys, TMS Edited by: Gell M, Kortovich CS, Bricknell RH, Kent WB, Radvich JF. 1984, 221.Google Scholar
- 25.Handbook ASM: Metals Process Simulation. ASM International, Ohio, USA; 2010.Google Scholar
- 26.Version 6.1. ESI software, France. 2007.Google Scholar
- 27.Rappaz M, Bellet M, Deville M, Snyder R: Numerical modeling in materials science and engineering. Springer-Verlag, Berlin, Germany; 2002.Google Scholar
- 29.Handbook ASM: Casting. ASM International, Ohio, USA; 2008.Google Scholar
- 34.Sahai V, Overfelt RA: Contact conductance simulation for alloy 718 investment casting of various geometries. Tran Amer F 1995, 103: 627–632.Google Scholar
- 35.Yuang XL, Lee PD, Brooks RF, Wunderlich R: The sensitivity of investment casting simulations to the accuracy of thermophysical properties values. Proceedings of the International Symposium on Superalloys, TMS 2004, 951.Google Scholar
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