Interfacial oxide analysis of ODS steel pressure resistance welded joint with different times

Pressure resistance welding is one of the most promising welding methods for joining oxide dispersion strengthened steel, and the interfacial oxides significantly affect the weld quality. In this study, the interfacial oxides were analysed through microstructural characterization and thermodynamic calculations for the joint with different welding times. The results demonstrate that the distribution of interfacial oxides transitions from a discontinuous band-like morphology to a randomly dispersed particulate configuration. As the welding time increases, the proportion of interfacial oxides exhibits a decreasing trend. After 8 ms welding, the proportion of interfacial oxides at different regions of the bonding interface fluctuates between 0.07 and 0.71, while with the 11 ms welding time, the proportion of interfacial oxides ranges from 0.05 to 0.33. The pre-weld sample surface consists of Cr-rich oxides and an amorphous Fe(Cr) oxide layer. After 8 ms welding, the amount of interfacial oxides decreases due to the welding deformation, and the type of interfacial oxides remains unchanged. The free surface transforms into a bonding interface, and the interfacial oxides consist mainly of Cr-rich oxide agglomerates as the welding time is extended to 9 ms. After 10 ms welding, further significant deformation occurs in the joint, leading to a reduction in interfacial oxides. In addition to Cr-rich oxides, small amounts of Cr(Ti) oxides are also present at the interface. When the welding time is 11 ms, most of the Cr-rich oxides decompose at elevated temperatures, and a few Y-Ti oxides were found at the original bonding interface. In the 12-ms welding sample, ripened, agglomerated Y-Ti oxides are present in the bonding joint.