Interfacial Microstructure and Mechanical Properties of High-Nitrogen Steel/Alumina Ceramic Heterogeneous Brazed Joints

Abstract:

To investigate a reliable joining method for heterogeneous joints between high-nitrogen steel and alumina ceramic, vacuum brazing of P580 high-nitrogen steel and alumina ceramic was carried out using AgCuTi filler metal. The influence of brazing temperature on the interfacial microstructure and mechanical properties of the joint was systematically analyzed. The results show that the optimal joint was obtained under the process parameter of 910 °C/10 min. Its interfacial structure was Al2O3/Cu3Ti3O/Ag(s,s)+Cu(s,s)+TiCu/TiN/high-nitrogen steel. A continuous and dense Cu3Ti3O reaction layer formed on the ceramic side, while TiN compounds were generated on the high nitrogen steel side. The maximum shear strength of the joint reached 53.74 MPa, with fracture occurring in the ceramic near the brazed seam. Excessively high or low temperatures led to discontinuous or fragmented reaction layers, thereby reducing joint strength. The Ag and Cu solid solutions exhibited good plasticity, which helped alleviate residual stress, while the thickness and continuity of the Cu3Ti3O reaction layer played a key role in the interfacial stress state and joint performance. This study provides a reliable brazing process solution for the heterogeneous joining of high-nitrogen steel and alumina ceramic.