Multiscale Modeling and Simulation of Directional Solidification Process of Ni-Based Superalloy Turbine Blade Casting

Qingyan Xu,Cong Yang,Ning Tang,Hang Zhang,Xuewei Yan,Baicheng Liu

doi:10.3390/met8080632

Abstract

Ni-based superalloy turbine blades have become indispensable structural parts in modern gas engines. An understanding of the solidification behavior and microstructure formation in directional solidified turbine blades is necessary for improving their high-temperature performance. The multiscale simulation model was developed to simulate the directional solidification process of superalloy turbine blades. The 3D cellular automaton-finite difference (CA-FD) method was used to calculate heat transfer and grain growth on the macroscopic scale, while the phase-field method was developed to simulate dendrite growth on the microscopic scale. Firstly, the evolution of temperature field of an aero-engine blade and a large industrial gas turbine blade was studied under high-rate solidification (HRS) and liquid-metal cooling (LMC) solidification processes. The varying withdrawal velocity was applied to change the curved mushy zone to a flat shape. Secondly, the grain growth in the aero-engine blade was simulated, and the grain structures in the starter block part and the spiral selector part in the HRS process were compared with those in the LMC process. The simulated grain structures were generally in agreement with experimental results. Finally, the dendrite growth in the typical HRS and LMC solidification process was investigated and the simulation results were compared with the experimental results in terms of dendrite morphology and primary dendritic spacing.

Highlights

Nickel-based superalloy blades [1–7], which possess excellent high-temperature creep resistance, have been proven to be successful in aero-engine and industrial gas turbines (IGTs)
To improve the high-temperature performance of superalloy blades, the columnar polycrystal and single crystal structures are favored, while the directional solidification (DS) techniques have become the choice for production over the past few decades
The most commonly used DS technique is the Bridgman technique [1], which was proposed by Bridgman and Stockbarger, and it has become the foundation of modern DS techniques

Summary

Introduction

Nickel-based superalloy blades [1–7], which possess excellent high-temperature creep resistance, have been proven to be successful in aero-engine and industrial gas turbines (IGTs). To improve the high-temperature performance of superalloy blades, the columnar polycrystal and single crystal structures are favored, while the directional solidification (DS) techniques have become the choice for production over the past few decades. High-rate solidification (HRS) [2] and liquid-metal cooling (LMC) [3]. DS techniques were developed with an enhanced ability to provide a high temperature gradient, and they are widely used both in industrial production and experimental investigations. In the HRS technique, the temperature gradient is established by the heating zone and the cooling zone, while the main heat transfer approach involves the radiation between the ceramic mold and the furnace wall.

Methods

Discussion

Conclusion