Influence of Different Base Materials on the Microstructure and Properties of Clad Rebar

Clad rebars of four different base materials (20MnSiV, 35# steel, 45# steel, and 55# steel) were successfully produced by a vacuum hot rolling process. A metallographic optical microscope (OM), electron backscatter diffractometer (EBSD), electron probe micro-analyzer (EPMA), and salt spray corrosion chamber were used to investigate the clad contour, properties, and composite interface microstructure of all four rebars. The results demonstrated that the thickness of the clad layer in the 20MnSiV/316L rebar had a more uniform distribution than those in the 35#/316L rebar, 45#/316L rebar, and 55#/316L rebar because 20MnSiV was more similar to 316L stainless steel in terms of deformation tendency. As the carbon content in the base layer increased, the amount of chromium-rich carbides increased noticeably. These large amounts led to a deficiency of chromium in the rebar composite interface and reduced corrosion resistance. Furthermore, bonding performance tests revealed that the bonding strength of the rebar composite interface not only depended on the amount of chromium-rich carbides, but also on the grain size of the composite interface. The larger the grain size of the composite interface, the lower the bonding strength was.