Theoretical And Experimental Research On Multi-roll Solid-liquid Cast-rolling Bonding Technology Of Metal Cladding Materials

Metal cladding materials are typical laminated metal cladding materials,which are key materials in aerospace,power electronics and other fields.The efficient forming and performance control technologies have always been an industry difficulty and an international research hotspot.Based on the research of the twin-roll solid-liquid cast-rolling bonding process of bimetallic clad pipes,a multi-roll solid-liquid cast-rolling bonding(MRSLCRB)process for metal cladding materials is proposed in this paper,aiming at the circumferential uneven product performance problem.The key problems,such as circumferential heat and mass transfer uniformity,process simulation and process window prediction,interaction mechanical behavior of cast-rolling area,bonding-forming mechanism and shape-performance control,are mainly solved.In order to analyze the circumferential heat and mass transfer uniformity,the basic thermal-physical parameters and the thermoplastic rheological constitutive model of materials are established.Meanwhile,a complete thermal resistance network coupled with multiple factors is established.The influences of the nominal roll radius,groove radius and molten pool height on the heat and mass transfer uniformity are analyzed under different layout modes.The thermal-fluid coupled simulation model is established,and the optimized process layout scheme and the equipment rudiment are obtained.Finally,the groove design criteria is put forward.In order to realize process simulation and process window prediction,a MRSLCRB equipment is designed independently.Parameters are optimized using finite difference method and numerical simulation,and equipment installation and debugging are completed.On this basis,the influences of the molten pool height,nominal cast-rolling velocity,cladding casting temperature,substrate preheating temperature,and substrate radius on the kissing point(KP)height and average outlet temperature of cast-rolling area are studied according to the thermal-flow coupled simulation model.Then,engineering calculation model is established and the reasonable process window is obtained,which lay a foundation for shorten the development cycle.In order to reveal the interaction mechanical behavior of cast-rolling area,the geometric characteristics of the cast-rolling area are analyzed according to the structural relationship.The geometric evolution relationship between the inlet section and the outlet section is established,and the metal flow behavior and mechanical diagram in the castrolling area are analyzed,which lay a theoretical foundation for the mechanical analysis.Then,the solid-solid rolling bonding stage is simplified to a pure wall-reducing mandrel rolling process.Based on the differential element method and the plane deformation assumption,the engineering calculation model of rolling force is derived and the influences of various process parameters are analyzed,which could provide theoretical guidance for equipment design.In order to illustrate the bonding-forming mechanism and shape-performance control,experimental researches are carried out using the self-built experimental platform,and the typical product defect types and causes are analyzed.The Cu/steel clad bars with metallurgical bonding interface and uniform circumferential performance are successfully prepared.Combined with the macroscopic and microscopic evolution of the cast-rolling area,thermal-fluid-microstructure coupled simulation,thermodynamic and kinetic analysis,the forming mechanism of the MRSLCRB process is revealed,and the interface reaction mechanism and interface evolution process are described.Feasibilities of fabricating single metal bar,metal cladding bar,bimetallic cladding pipe,metal cladding strand wire,special-section cladding material and finned reinforced cladding material are analyzed based on the experimental platform and numerical simulation,which enrich the special groove cast-rolling bonding theory and initially construct the rudiment of the advanced functional cladding material cast-rolling process theoretical system.