The Influence of the Melt-Pouring Temperature and Inoculant Content on the Macro and Microstructure of the IN713C Ni-Based Superalloy

Hubert Matysiak,Rafal Cygan,Krzysztof Dobkowski,Jacek Nawrocki,Jan Cwajna,Mateusz Koralnik,Krzysztof J Kurzydlowski,Malgorzata Zagorska,Boguslawa Adamczyk-Cieslak,Alicja Balkowiec

doi:10.1007/s11837-015-1672-5

Abstract

The aim of this work was to determine the effect of melt-pouring temperature T m and inoculant (cobalt aluminate—CoAl2O4) concentration in the prime coat of the shell mold on the macro- and microstructure of the IN713C superalloy. The results show that cobalt aluminate is an effective modifier of the IN713C superalloy, which causes refinement of the equiaxed grains (EX) and a reduction of the fraction and size of the columnar grains on the casting surface. Also, the melt-pouring temperature in the range of 1450–1520°C was found to influence the mean EX grain size. Based on the results of differential thermal analysis of the alloy and detailed microstructure characterization, a sequence of precipitations has been proposed that advances current understanding of processes that take place during alloy solidification and casting cooling.

Highlights

IN713C is a nickel-based superalloy adequate for use at high temperatures
The works[21,22] present results that show that when the melt-pouring temperature is constant and the variable is the inoculant content, there are no meaningful differences between secondary dendrite arm spacing (SDAS) values, despite significant differences in the grain size, which is confirmed by our results
By taking into account the parameters of our process discussed earlier, as well as the area selection for determining SDAS, the minor changes in cooling rate, thermal gradient, and solidification rate in this study provide evidence for a correlation between SDAS and the melt-pouring temperature or the inoculant content

Summary

Introduction

IN713C is a nickel-based superalloy adequate for use at high temperatures. The designers of the large aircraft turbofan engine GP7200 selected this alloy for the production of LPT blades and LPT vane clusters. These complicated castings must meet all quality requirements, which in this case are highly strict. Examined are the chemical composition (the content of the main alloying elements and the trace elements) and the mechanical properties (employing static tensile testing at elevated temperatures and stress rupture tests)

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Conclusion