Abstract:The deformation behavior of GH4169 superalloy under room-temperature uniaxial tension was investigated through synchronized mesoscopic digital image correlation (DIC) and electron backscatter diffraction (EBSD) in-situ characterization techniques. Results show that in the field of grain deflection dynamics, through quantitative analysis using the independently developed M-DIC software, during uniaxial tension with significant bidirectional rotation along the tensile axis and the stress level of 1100 MPa, oscillatory rotation of ±0.6° can be obtained, and microvoids are generated at the grain boundaries with 45° to the stress axis. EBSD crystallographic analysis demonstrates the load-dependent slip system evolution: in the initial stage, the soft-oriented systems with high Schmid factor (>0.4) is activated and then transformed into hard-oriented systems during cross-slip, generating parallel slip bands and dislocation pile-ups at grain boundaries. During the uniaxial tensile process, the characteristic of strain energy accumulation is observed, which follows a two-stage accumulation pattern: initial grain boundary localization (Stage I) and intragranular propagation (Stage II). Ultimately, the intergranular cracks are initiated at triple junctions, and the twin boundaries exhibit superior mechanical stability compared with the large-angle grain boundaries. Deformation texture characteristics indicate the copper-type components, including C{112}<11>, S{123}<63>, and B{110}<10>. The complete deformation sequence is as follows: cross-slip of soft-oriented slip systems→initiation of dislocation slip→strain partitioning through grain rotation→intergranular stress concentration→damage dominated by boundary cracking. The cross-scale deformation mechanism revealed in this study provides critical guidance for the crystal boundary engineering to optimize nickel-based superalloys.