Creep Life Assessment of the IN738LC Superalloy in V94.2 Gas Turbine First Stage Blade

Articles in Press

Document Type : Original Article

Authors

• Alireza Toosi ¹
• Fatemehsadat Sayyedan ²

¹ Department of Materials Science and Engineering, Faculty of Engineering, Ferdowsi University of Mashhad

² Department of Materials Science and Engineering Faculty of Engineering Ferdowsi University of Mashhad, Mashhad

10.22067/jmme.2025.91255.1174

Abstract

The aim of this research was to estimate the creep life of the V94.2 gas turbine first stage blade made of Inconel 738 LC superalloy using non-destructive, destructive, and computational methods. Metallographic and microstructural examinations were performed using field emission scanning electron microscopy (FESEM) and mechanical properties tests. Visual inspection and liquid penetrant were performed on the blade followed by comparing the microstructure of the root, leading edge, and trailing edge. Mechanical properties of the blade, including ambient and high temperature tensile tests, hardness, and stress-rupture of the middle part of the blade and the root, were compared with the minimum properties allowed for service. The blade life was assessed using the Larson-Miller parameter and the creep residual life fraction relationship. The results revealed that the blade root has maintained its cubic structure compared to the leading and trailing edges due to the low operating temperature at this part. The phase fraction of secondary gamma prime particles at the root was clearly visible, unlike the leading and trailing edges. Considering the yield and ultimate tensile strength of the airfoil and blade higher than those of the minimum properties allowed for service, the first stage blade will be reusable in case of restoration and rejuvenation of the microstructure. The blade life was estimated to be 10032 h, which was less than the required period for overhaul, i.e. 33000 h. So, structural modification and rejuvenation of the blades are essential and its subsequent use will be unimpeded for 10032 h.

Keywords

• Creep life
• Turbine blade
• Ni-based Superalloy

Main Subjects

• Mechanical Metallurgy

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