Interfacial microstructure and strengthening mechanism of stainless steel/carbon steel laminated composite fabricated by liquid-solid bonding and hot rolling

Abstract

Stainless steel/carbon steel (SS/CS) laminated composites were prepared by liquid-solid (L-S) bonding followed by hot rolling under different reduction rates, and the microstructure characteristics at the cladding interface zone and their influences on the interfacial bonding strength of the SS/CS laminated composites were analyzed. A metallurgical bonding interface was obtained by the L-S bonding method, and coarse equiaxed grains, decarburization layer and oxides formed at the cladding interface zone. During hot rolling, heterodeformation occurred in the SS/CS laminated composites, resulting in asynchronous dynamic recrystallization and the refinement of grains in both SS and CS. The thickness of the decarburization layer and elements diffusion distance obviously decreased after hot rolling, while the ratio of the diffusion distances of Cr and Ni elements to the width of the decarburization layer increased with increasing reduction rates. Additionally, the oxides at the cladding interface zone transformed into hybrid inclusions after hot rolling, and the maximum equivalent diameter and volume fraction of the inclusions decreased with increasing reduction rates. The interfacial shear strength of the L&R bonded SS/CS laminated composites increased with increasing reduction rates, and a maximum value of 400 MPa was obtained at a reduction rate of 75%, which is 34% higher than that of the L-S bonded SS/CS laminated composite due to the grain refinement, improved relative diffusion distance of Cr and Ni elements, reduced and refined inclusions at the cladding interface zone.