This work examines the micromechanical deformation of GH4169 superalloy, focusing on how δ phase characteristics, including content (area fraction), morphology, and distribution, affect grain scale stress/strain partitioning. By combining microstructural characterization with crystal plasticity finite element modeling, we elucidate the mechanisms behind the unusual mechanical evolution after cold rolling (0–70%) and solution treatment. The results show that higher cold rolling reduction not only raises the area fraction of the δ phase from 0.27% to 4.56% but also alters its morphology and size. The coexisting spheroidal, short-rod-like, and needle-like particles evolve primarily via elongation along the long axis and dissolution along the short axis, resulting in overall coarsening. Concurrently, the distribution shifts from intragranular sites toward grain boundaries and triple junctions. These microstructural evolutions result in hard-soft grain strain partitioning, where strain localizes in hard grains but spreads extensively in soft grains. The significant strength degradation observed at 70% deformation is primarily due to excessive δ phase precipitation, which weakens solid-solution strengthening. Compared to morphology, the distribution of the δ phase exerts a more pronounced influence on slip activation and local stress evolution. Uniformly dispersed intragranular δ particles promote multi-slip activity and effectively regulate matrix stress distribution. • Multiparameter δ Phase Analysis: Breaks through traditional single parameter (volume fraction) limitations by integrating volume fraction, morphology, and distribution of δ phase to understand their coupled influence on GH4169's micromechanical deformation. • Quantitative Processing-Structure-Property Chain: Establishes a novel quantitative correlation chain: Cold Rolling Reduction → δ Phase Characteristics (Content/Morphology/Distribution) → Microscopic Strain Partitioning → Macroscopic Property Evolution, elucidating the processing-microstructure-performance mechanism. • Synergistic CPFEM Inversion & Visualization: Develops a crystal plasticity finite element (CPFEM) model that simultaneously inverts all three δ phase parameters (morphology, distribution, content) and achieves dynamic visualization of microscopic stress/strain fields, capturing the hard-soft grain strain partitioning effect. • Mechanism of Strength Degradation Uncovered: Deciphers the fundamental micromechanical cause (via strain/stress field analysis and strain partitioning) underlying the macroscopic strength degradation observed at high (70%) deformation levels.
Ye et al. (Sun,) studied this question.