Microstructure and coordination mechanism of interface of stainless steel/carbon steel cladding plate prepared by vacuum diffusion bonding

Vacuum diffusion bonding (VDB)-prepared 304 austenite stainless steel (SS)/Q235 carbon steel (CS) clad plates were the focus of this study. Specifically, the metallurgically bonded interfaces, which are known to have good mechanical properties, were investigated. The microstructures of the interfaces were extensively investigated using transmission electron microscopy (TEM). The characterization results revealed the existence of annealing twins and lath martensite precipitates at the interface; the high strength and plasticity at the interface were determined to be attributed to these features. In addition, the distribution and Burgers vector of dislocations at the ferrite-austenite interfaces were investigated by using two-beam method of TEM electron diffraction contrast image (EDCI) technology and high-resolution TEM imaging. As a result, the coordination mechanisms at the ferrite-austenite interfaces during the deformation of the SS/CS clad plates were clarified; the observations include: (1) the perfect dislocation with the Burgers vector a2 < 111> in the ferrite moved across the interface and formed a perfect dislocation with the Burgers vector 2a < 110> in the austenite; (2) the ferrite lattice was joined to the perfect dislocation with the Burgers vector 2a < 110> in the austenite; and (3) the ferrite lattice continuously extended across the interface, and was connected to the austenite lattice. According to the results on the Burgers vector of dislocations, two types of dislocation reactions occurred at the ferrite-austenite interfaces during the deformation. Lastly, the transfer matrix of the orientation relationship (OR) between austenite and ferrite was calculated. The results revealed that the OR differed from that of the conventional OR between body-centered cubic and face-centered cubic structures; thus, it can be concluded that the preparation of SS/CS clad plates via VDB technology may lead to the formation of a unique OR between ferrite and austenite.

Automated summary

This study focused on the vacuum diffusion bonding (VDB)-prepared 304 austenite stainless steel (SS)/Q235 carbon steel (CS) clad plates, with a particular investigation into the metallurgically bonded interfaces that exhibit good mechanical properties. Microstructures of the interfaces were extensively studied using transmission electron microscopy (TEM), revealing the presence of annealing twins and lath martensite precipitates at the interface, contributing to the high strength and plasticity. Additionally, dislocation distribution and Burgers vector at the ferrite-austenite interfaces were analyzed, showing different dislocation reactions during deformation and a unique orientation relationship (OR) between ferrite and austenite in SS/CS clad plates prepared via VDB technology.