Eutectic melting behavior between nuclear materials is a critical issue in severe accidents. The eutectic reaction between boron carbide (B₄C) and stainless steel (SS) can lead to the early melting of control rods, forming a eutectic melt that may spread widely. The eutectic melting temperature varies with heating rate, especially under severe accident conditions, where control rod heated rapidly. In this study, differential thermal analysis and Thermogravimetric analysis were used to investigate eutectic melting behavior. Bulk B₄C and 316L SS samples were heated at rates of 2.5–20 K/min up to 1673 K. The eutectic melting temperature at different heating rates were obtained by the DTA curves and TG curves of the samples, revealing a trend of increasing eutectic melting temperature with higher heating rates. Post-experimental SEM and EDS analyses offered comprehensive insights into the microstructure and elemental distribution at the solidification interface. Results show a distinct three-layer structure across the cross-section of the melt, with a central eutectic diffusion layer. At lower heating rates, a dense and uniform diffusion layer was observed, whereas higher rates resulted in a rougher, more dispersed diffusion layer. The thickness of the diffusion layer decreased as heating rate increased. And molar concentration analysis of elements within the diffusion layer indicated a reduction in Fe molar percentage in the B-C-Fe-Cr quaternary system. This study provides critical support for understanding eutectic melting behavior and modeling eutectic reactions under severe nuclear reactor accident conditions.