Interfacial Microstructure and Properties of Clad Rebar Prepared by Clean-Interface Assembly and Vacuum Hot-Rolling

Abstract

Stainless steel cladded rebars were successfully prepared by clean-interface assembly and vacuum hot-rolling process. The interfacial microstructure and properties of the clad rebars were investigated by scanning electron microscope (SVM), transmission electron microscope (TEM), and electron probe X-ray microanalyser (EPMA). The results demonstrated that owing to the diffusion of carbon, decarburised (roughly 50 μm) and composite zones (roughly 60 μm) formed on each side of the composite interface. The decarburized zone features a single ferrite texture, hence, a relatively low micro-hardness of 138HV while, due to the large amount of martensite formed within it, the composite zone has a relatively high micro-hardness of 218HV. The salt spray test showed that the corrosion rate of the clad rebars is close to that of the round stainless bars, and is approximately one-tenth that of the carbon rebars. In addition, a layered multipass welding process was used to produce a cladding joint, which was determined to have a tensile strength greater than the standard value of the parent material and excellent corrosion resistance.