Abstract <p>In this study, the effects of solution temperature on the high-temperature tensile properties and microstructure evolution of GH4738 superalloy were thoroughly examined employing multiscale characterization approaches, namely scanning electron microscope (SEM), electron backscatter diffraction (EBSD), as well as transmission electron microscope (TEM). The results indicated that within the solution temperature range of 1000–1080&#xa0;°C, the tensile strength of the alloy increased slightly with increasing solution temperature, while its ductility decreased significantly. The alloy exhibited the optimum overall high-temperature mechanical performance at 760&#xa0;°C after solution treatment at 1000&#xa0;°C. EBSD characterization of the deformed microstructures near the high-temperature tensile fractures indicated that the grain size coarsened with increasing solution temperature, whereas the density of geometrically necessary dislocations (GNDs) decreased. SEM analysis revealed that as the solution temperature rose, the quantity of Cr-enriched grain boundary M₂₃C₆ carbides progressively increased, with their morphologies transitioning from isolated particles to intermittent chains and ultimately to a continuous distribution. Simultaneously, the size distribution of globular γ′ precipitates evolved from bimodal to unimodal. With increasing solution temperature, the fracture mode shifted from transgranular fracture to a mixture of transgranular and intergranular fracture. TEM results indicated that stacking fault shearing was the predominant deformation mechanism in high-temperature tensile tests at 760&#xa0;°C.</p> Graphical Abstract <p></p>