<p>To elucidate the regulatory mechanism of the induction refining process on the microstructure evolution and mechanical properties of self-propagating in situ-synthesized Invar alloy, this study systematically investigates the effects of refining slag ratios and refining times. Based on phase diagram thermodynamics and slag coexistence theory, a CaO–Al₂O₃–SiO₂–MgO refining slag system was optimally designed, revealing the regulation law of temperature on the surface tension and viscosity of the slag system. The results indicate that the refining slag ratios and refining times dominate the microstructure and property evolution through dual mechanisms of grain refinement and precipitate regulation. Appropriately increasing the slag amount significantly reduced inclusion content, suppressed heterogeneous nucleation, and increased nucleation rate, thereby achieving grain refinement. Extending the refining time promoted deep purification of the melt and enabled carbides to undergo a complete evolution process from precipitation, Ostwald ripening, to partial redissolution. Under the conditions of a 10% refining slag ratio and 30&#xa0;min of refining time, the synergistic effect of fine-grain strengthening and precipitation strengthening is most significant, with the tensile strength reaching 534&#xa0;MPa and the fracture elongation reaching 34.75%. This study reveals the intrinsic correlation between refining process parameters and the microstructure and mechanical properties of Invar alloy, providing a mechanistic basis and process reference for the preparation of high-performance Invar alloy via self-propagating in situ synthesis coupled with refining.</p> Graphical Abstract <p></p>