Interface Characteristics of GCr15/45 Carbon Steel Composite Billet Produced by Electroslag Remelting Cladding

In the present study, a GCr15/45 carbon steel composite billet is manufactured by the new electroslag remelting cladding (ESRC) method and a systematic analysis of the interface characteristics including the bonding state, element transition, microstructure evolution and tensile strength is carried out. It illustrates that an appropriate smelting power is beneficial to obtain a metallurgical bonding interface. Based on the temperature variation characteristics of the composite system, the bonding state of the bimetals (interface) changes gradually from entrapped slag defect to metallurgical bonding at the early stage of ESRC process, and the widths of elements transition and heat-affected zone (HAZ) become proportional to the composite height. It has an obvious influence on the grain size and precipitated phase at bimetallic interface. Tensile test results on both as-cast and annealed samples prove that the bimetallic interface is not the weakest zone as the fracture occurred at the roll core (45 carbon steel) side. In addition, an appropriate isothermal spheroidization annealing treatment is beneficial to refine the austenite grains and optimize the microstructure of the composite billet.