Abstract: Given the current lack of research on equiaxed/single crystal bimetal superalloys, K447A/DD412 dual-alloy dual-property test bars were successfully fabricated via a secondary pouring process in this study. The effect of hot isostatic pressing(HIP) on their microstructure was investigated. Analysis of the as-cast microstructure revealed a wide transition zone between the two alloys with no interfacial oxidation, indicating a good metallurgical bond. The overall microstructure of the bimetal test bar could be divided into four regions: K447A, DD447, a compositional transition zone(CTZ), and DD412. Significant compositional and microstructural differences were observed among these regions. The area fraction of eutectic and carbides gradually decreased from K447A to DD412, while the area fraction of the dendritic γ' phase increased correspondingly. After hot isostatic pressing treatment, microporosity was essentially eliminated. The area fraction of eutectic and carbides decreased overall, though their morphology did not change significantly. Additionally, the morphology of the dendritic γ' phase was refined, and its area fraction increased. It should be noted that the HIP-treated microstructure still exhibited issues such as excessively large γ' phase size, which requires further optimization through subsequent solution and aging heat treatments. This study provides a theoretical and experimental basis for the development of dual-alloy dual-property blisks.