Study On Mechanism And Interface Control Of Twin-Roll Casting With Roll Vibration For Ti/Al Clad Sheet

Ti/Al laminated composites combine the advantages of low density,high strength,corrosion resistance,friction resistance,high temperature resistance of titanium metal and high electrical and thermal conductivity of aluminum metal,and have become a key material for aerospace,power electronics,battery energy and other fields.The solid-liquid twin-roll casting technology integrates continuous casting and rolling into one process,which has the two necessary conditions of high temperature and high pressure to enhance the metallurgical bonding of heterogeneous metal interfaces,and is a new method for the production of laminated metal composites.However,problems such as process instability,liquid-based tissue defects and uneven interfacial compounding still occur during the actual production process using this method.In response to this series of technical problems,this paper puts forward the new technology of twin-roll casting with roll vibration to composite,which achieves the effects of “disturbed flow”,“stimulated nucleation”,“broken dendrite” and “asynchronous rolling” based on “high temperature”and “high pressure” of traditional twin-roll casting.In order to study the effect of roll vibration on the flow,heat transfer and solidification behavior of molten aluminum,a solid-liquid composite numerical model of twin-roll casting with roller vibration was established,and the evolution laws of velocity field and temperature field of molten aluminum during the vibration period was obtained,as well as the time-domain characteristics of velocity and temperature of molten aluminum at the center and boundary of the molten pool during the twin-roll casting composite process.The flow,heat transfer and solidification behavior of molten aluminum is also affected by key process parameters and their interaction with roll vibration.Internal comparison models of four key process parameters including casting-drawing speed,roll speed,casting temperature and roll heat transfer under two vibration conditions of twinroll casting with vibration and traditional twin-roll casting were established,and the effect of the interaction between roll vibration and different process parameters on the solidification and flow of the molten aluminum was obtained,as well as the effect on the time-domain characteristics of flow rate,pressure,and temperature of the molten aluminum at the center and boundary of the molten pool,through the analysis of the effect of different process parameters on the behavior of the molten aluminum and the control laws of the roll vibration on different process parameters.According to the composite process procedure of twin-roll casting with roll vibration obtained from numerical calculations,multiple types of Ti/Al clad plates were prepared by the Φ 160 mm × 170 mm type twin-roll casting machine with roll vibration selfdeveloped by the subject group,and tensile and peeling tests were carried out by using a universal testing machine,to obtain the effect of roll vibration on the tensile and peeling strength of the Ti/Al clad plates.The multi-dimensional characterization and phase detection on the tensile fracture,peeling section and bonding interface of the Ti/Al clad plates were carried out by means of SEM and XRD,and the evolution laws of microstructure,element distribution and intermetallic compounds with roll vibration were obtained,as well as the reasons for strengthening the mechanical properties of Ti/Al clad plates.The composite mechanism of the Ti/Al clad plates and the mechanism of the effect of roll vibration on its composite mechanism were analyzed.The stable intermetallic compound layer cannot be formed at the interface when the molten aluminum is combined with the titanium strip for a short time.The Ti/Al clad plates formed by twin-roll casting were annealed,and the tensile and peeling tests were carried out.Then they were compared with the Ti/Al clad plates before annealing.The effects of annealing on the tensile strength and peeling strength of the Ti/Al clad plates were obtained.The same microscopic characterization methods were used to analyze the annealed Ti/Al clad plates,and the mechanism of annealing to improve the interfacial composite quality and the influence mechanism of roll vibration on the strengthening behavior of the material during annealing were obtained.Annealing transforms the “direct bonding” of the “two-phase” mechanical engagement into the “transition bonding” of the“three-phase” intermetallic compound layer,which achieves a mode change of the layered metal composite.