니켈기 초내열합금의 기계적 특성 예측을 위한 전산 기법 개발

Abstract

In this doctoral thesis, a numerical model to predict mechanical properties of Ni-base superalloys is proposed. The thesis is applied to an aspect of Ni-base superalloys for turbine disk applications.

The proposed model is developed by modifying and combining previous models, and considers various microstructural factors based on deformation mechanisms. Modifications are made so that as many necessary model parameters as possible, whose values have been obtained from mechanical measurements and microstructural observation, can be determined from a thermodynamic calculation and a precipitation kinetics simulation. The resulting model can reproduce tensile properties, creep resistance and fatigue damage tolerance with good correlation with experimental data. The applicability and limitation of the proposed model as an alloy design tool for new Ni-base disk superalloys are discussed in this thesis.