Microstructure and Interface Fracture Characteristics of Hot Rolled Stainless Steel Clad Plates by Adding Different Interlayers

Series of 316L/Q235 stainless steel clad plates are successfully fabricated by hot rolling with different interlayers of ferrum (Fe), nickel (Ni), and niobium (Nb) foils. The interface microstructure, interfacial characteristics, shear performance, tensile properties, and fracture morphologies of clad plates are investigated using optical microscope (OM), ultra-depth microscope, scanning electron microscope (SEM), electron probe microanalysis (EPMA), transmission electron microscope (TEM), and universal testing in detail. It is observed that the addition of Fe interlayer has rare effect on the interface element diffusion. Clad plate with Fe interlayer can only obtain poor tensile and shear properties, which is attributed to severe oxidation at the clad interface. On the contrary, the addition of Ni and Nb interlayers can both effectively inhibit the diffusion behavior of interface carbon element and remarkably reduce interfacial weak areas of carburized and decarburized layers. This is due to that Ni interlayer can sharply slow down the carbon diffusion velocity, and Nb interlayer can suppress interface carbon diffusion by reacting with carbon element and forming niobium carbide phase. After adding Ni or Nb interlayers, stainless steel clad plates can obtain superior interfacial bonding strength, tensile strength, and fracture elongation, eventually achieving the purpose toward strengthening and toughening the interface.