Hot-dip aluminizing of stainless steel and investigation of interfacial intermetallics

The types and evolution of Fe-Al intermetallic compounds (IMCs) serve as the theoretical foundation for regulating the microstructure and properties of the aluminum/steel joining interface. In this study, through hot-dip aluminizing experiments of stainless steel at 700–1000°C for 2–30 s, the formation temperatures and durations of various interfacial IMCs were identified, the growth kinetics of IMC layers were analyzed, and the structural similarities and differences among the compounds were compared. With increasing hot-dipping temperature and time, Fe 4 Al 13 formed at 700°C for 2 s, Fe 2 Al 5 and FeAl 2 emerged at 750°C for 30 s, and FeAl appeared at 950°C for 2 s. The total thickness of the IMCs initially decreased with rising temperature, then stabilized, and subsequently increased. An anomalous reduction in total thickness with prolonged time was observed at 750°C, attributed to the formation of multi-layered IMCs at the interface, which decelerated the growth rate of Fe 4 Al 13 . EBSD analysis revealed that the average grain size and texture intensity of the four IMCs followed the order: Fe 2 Al 5 > Fe 4 Al 13 > FeAl > FeAl 2 . All the IMCs predominantly exhibited high-angle grain boundaries. The crystallographic symmetry was relatively poor for Fe 2 Al 5 and FeAl, moderately improved for Fe 4 Al 13 , and optimal for FeAl 2 .