Simultaneously enhanced strength-ductility synergy and corrosion resistance in liquid-solid bonded stainless steel cladding carbon steel plate by hot rolling and annealing treatment

Abstract

Liquid-solid (L-S) bonded stainless steel/carbon steel (SS/CS) laminated composites have strong metallurgical bonding interface, while the solidification structure of SS deteriorates the mechanical properties and corrosion resistance. In this study, hot rolling and annealing were proposed to regulate the microstructures and balance the performance of L-S bonded SS/CS clad plates. SS cladding CS plates were prepared by horizontal continuous liquid-solid composite casting and hot rolled at 1200 °C with a reduction rate of 90%, and annealed at 1000 and 1050 °C for 30 min. The microstructural evolution was studied by scanning electron microscope and electron back-scatter diffraction, elemental distribution was investigated by electron probe microanalysis. Microhardness, tensile test and anodic-cathodic polarization test in a 3.5% NaCl solution were carried out on hot-rolled and annealed SS cladding CS plates, and the mechanism for the simultaneous enhancement of strength-ductility synergy and corrosion resistance by hot rolling and annealing was analyzed. Annealing at 1050 °C resulted in excellent properties with tensile strength of 550 MPa and elongation of 50%, corrosion potential of −0.21 V and corrosion current density of 0.13 μA cm−2. The strength and ductility of the SS cladding CS plate were synergistically improved by a strong metallurgical bonding cladding interface, high frequency of low-Σ CSLs and refinement of grains in 304 SS. The low-Σ CSLs in 304 SS restricted the formation of carbides in the carburized layer and broke down the connectivity of random boundaries, improving the corrosion resistance.