Investment casting of nozzle guide vanes from nickel-based superalloys: part II – grain structure prediction

Agustin Jose Torroba,Javier Llorca,Mehdi Rahimian,Loic Calba,Laura Maestro,Efrain Carreño-Morelli,Srdjan Milenkovic,Ilchat Sabirov,Ole Koeser

doi:10.1186/s40192-014-0026-4

Abstract

AbstractThe control of grain structure, which develops during solidification processes in investment casting of nozzle guide vanes (NGVs), is a key issue for optimization of their mechanical properties. The main objective of this part of the work was to develop a simulation tool for predicting grain structure in the new generation NGVs made from MAR-M247 Ni-based superalloy. A cellular automata - finite element (CAFE) module is employed to predict the three-dimensional (3D) grain structure in the as-cast NGV. The grain structure in the critical sections of the experimentally cast NGV is carefully analyzed, the experimental results are compared with the modeling outcomes, and the model is calibrated via tuning parameters which govern grain nucleation and growth. The grain structures predicted by the calibrated model show a very good accordance with the real ones observed in the critical sections of the as-cast NGV. It is demonstrated that the calibrated CAFE model is a reliable tool for the foundry industry to predict grain structure of the as-cast NGVs with very high accuracy.

Highlights

Solidification microstructure is of great importance for controlling the properties and the quality of the nozzle guide vanes (NGVs) produced via investment casting
It is demonstrated that the calibrated cellular automata - finite element (CAFE) model is a reliable tool for the foundry industry to predict grain structure of the as-cast NGVs with very high accuracy
The second part of our work aims to develop the CAFE module for grain structure prediction in the new generation NGVs to be produced via investment casting in a real plant process

Summary

Introduction

Solidification microstructure is of great importance for controlling the properties and the quality of the nozzle guide vanes (NGVs) produced via investment casting. Phase-field models based on the rigorous framework of reversible thermodynamics [2,3] have been developed to describe both the solidification of pure materials [4] and binary alloys [5,6]. They have been used extensively to simulate numerically dendritic growth into an undercooled liquid [7,8,9,10]. Systems with three phases as well as grain structures with an ensemble of grains of different crystallographic orientations have been modeled by the phase-field method using a vector-valued phase

Methods

Results

Conclusion