American Journal of Materials Engineering and Technology
ISSN (Print): 2333-8903 ISSN (Online): 2333-8911 Website: http://www.sciepub.com/journal/materials Editor-in-chief: Serge Samper
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American Journal of Materials Engineering and Technology. 2017, 5(1), 14-23
DOI: 10.12691/materials-5-1-3
Open AccessArticle

On the Role of Boride in the Structural Integrity of a Turbine Disc Superalloy’s Solid State Weld

K.M. Oluwasegun1, , J.O Olawale1, M.D. Shittu1, O.O. Ige1, P.O. Atanda1, O.O. Ajide2 and L.O. Osoba3

1Department of Materials Science and Engineering, Obafemi Awolowo University, Ile-Ife, Nigeria

2Department of Mechanical Engineering, University of Ibadan, Nigeria

3Department of Metallurgical and Materials Engineering, University of Lagos, Nigeria

Pub. Date: October 13, 2017

Cite this paper:
K.M. Oluwasegun, J.O Olawale, M.D. Shittu, O.O. Ige, P.O. Atanda, O.O. Ajide and L.O. Osoba. On the Role of Boride in the Structural Integrity of a Turbine Disc Superalloy’s Solid State Weld. American Journal of Materials Engineering and Technology. 2017; 5(1):14-23. doi: 10.12691/materials-5-1-3

Abstract

This work reports the melting of boride precipitates along the grain boundary of a supposedly solid state welding of a polycrystalline superalloy, and discusses its attendant effect on the hot ductility behaviour of the alloy. Nickel-based superalloy used for this study was previously processed by hot extrusion of argon atomized powered followed by forging. The alloy was solution heat treated at 1120 °C, aged at 760 °C and subsequently air cooled to room temperature. Thereafter, it was welded by inertial friction welding (IFW) at a forging pressure of 250 MPa and finally stressed relieved at 760 °C for 8 hours. The microstructures of welded samples were studied by scanning and scanning transmission electron microscopes. Gleeble hot ductility test was carried out on tensile specimen machined from the welded sample. The microstructures of the welded alloy shows that boride precipitates liquated along the grain boundary within the heat affected zone (HAZ) as a result of rapid heating of IFW. The results of hot ductility test revealed that the melting of boride lowered the hot ductility of the alloy. It was concluded that the boride precipitates liquated along the grain boundary of the nickel-based superalloy during solid state welding and lowered its hot ductility.

Keywords:
superalloy solid state welding boride precipitates grain boundary hot ductility welding

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