Interface Structure Change and Carbon Diffusion of Stainless Steel-Carbon Steel-Laminated Composite under High-Temperature Condition

In this paper, the interface structure and carbon diffusion of stainless steel–carbon steel-laminated composites after heating at different temperatures and times are studied. The experimental results show that the interface structure of the stainless steel–carbon steel-laminated composite is composed of a decarburization layer of carbon steel, an intermetallic compound layer and a carburization layer of stainless steel. When the heating temperature is lower than 500 °C, the interface structure basically does not change over heating time. When the heating temperature is between 550 and 850 °C, as the heating time increases, the stainless steel undergoes sensitization, and the carbon diffuses from carbon steel to stainless steel. The diffusion rate is positively related to the susceptibility to the intergranular corrosion of stainless steel, resulting in an increase in the thickness of the decarburization layer of carbon steel, the further carburization of stainless steel and an increase in the degree of sensitization of the stainless steel surface. When the heating temperature is larger than 900 °C, as the heating time increases, carbon steel undergoes austenitization, stainless steel undergoes solid solution strengthening, and carbon diffuses from the stainless steel to the carbon steel, resulting in the disappearance of the decarburization layer of carbon steel and the carburization layer of stainless steel. In this paper, a reference is provided for the heat treatment temperature set and the service temperature upper limit of the stainless steel–carbon steel-laminated composite.