Damage Evolution during Compressive Hold Sustained Peak Low Cycle Fatigue of a Ni-Based Single-Crystal Superalloy

作者：S. Huang, M. Karadge, D. Konitzer, Shivam A. Patil, A. Suzuki · 年份：2016 · DOI：10.7449/superalloys/2016/superalloys_2016_959_967 · 研究领域：High Temperature Alloys and Creep、Metallurgy and Material Forming、Microstructure and Mechanical Properties of Steels

The damage evolution in a Ni-base single-crystal superalloy during compressive hold sustained peak low cycle fatigue (SPLCF) was investigated by conducting series of interrupted SPLCF tests using Ren N5 at 982 and 1093 C. Evolution of hysteresis loops and microstructure in the bulk away from surface cracks were analyzed to understand bulk damage accumulation. Tensile stress developed during SPLCF was found to be a key factor for crack propagation and life. Bulk deformation away from cracks showed a signature of dominant creep deformation, including ' rafting and formation of interfacial dislocation networks. Crack depth measurements along with detailed microstructural investigations of cracks were performed to understand crack growth behavior. Based on the experimental results, a comprehensive SPLCF crack growth model was developed by combining a finite element method (FEM) simulation of oxide induced crack growth and linear elastic fracture mechanics (LEFM) based approach.