Numerical Simulation And Experimental Research On Bonding Mechanism Of Solid-liquid Cast-rolling Of Bimetal Clad Strip

Using composite technology to combine several kinds of metal components together and promoting them to combine firmly at the interface in a layered manner, layered mental composites materials synthesize the advantage of all components, creating new-metal materials, which are widely used in aerospace, Power electronic, chemical industry, shipbuilding and automobile fields. Explosive and rolling bonding are the main forming process of the bimetal clad plate, which belongs to the typical solid state bonding technology, and its industrial application has been widely used. In recent years, the solid-liquid bonding technology based on twin roll cast-rolling technology has become the leading direction in the research field of the near end forming of bimetal clad plate, which has attracted wide attention from domestic and foreign scholars.This paper takes National invention patent ―double metal clad plate pulse solid-liquid cast-rolling equipment and method(ZL201510040540.7)‖ as the background, under the support of the National Natural Science Foundation of China ―undamental research on current enhanced bonding technology of Cu/Al clad strip cast-rolling(NO.51474189)‖, he bonding mechanism of Cu/Al interface in the composite area of the cast-rolling as the main research object, focuses on numerical simulation of the thermodynamic behavior of the interface, the transformation of the conventional twin roll cast rolling mill and the experimental study on the bonding mechanism and feasibility of Cu/Al clad strip cast-rolling.In order to reveal the distribution of temperature field and flow field in Cu/Al clad strip with solid-liquid cast rolling, creating a two-dimensional heat flow coupled model which is in the process of roll cast rolling with FLUENT software, simulating and analyzing the influence of the casting speed, preheating temperature, copper strip thickness, pouring temperature of liquid aluminium and other factors on the location of kiss point and interface temperature. The results show that, improving casting speed and the preheating temperature of copper, reducing the thickness of the copper strip can effectively increase the temperature of composite interface and liquid region. Meanwhile, increasing the pouring temperature of molten aluminum can improve flow condition of the liquid metal in cast rolling region.In order to develop the bonding process of Cu/Al clad strip with solid-liquid cast rolling, the ?160×150mm experimental twin-rollers continuous caster was reformed, the experiment platform of solid-liquid cast rolling of Cu/Al clad strip was designed and constructed. Based on the numerical simulation results, the experimental parameters such as casting speed, casting temperature, casting speed and so on are determined. Under these conditions, the cast rolling speed of 2m/min, the pouring temperature of 690℃, molten pool height of 30 mm, strip temperature of 25℃, the thickness of 2mm Cu/Al clad strip was successfully prepared. Test results of interfacial properties and mechanical properties of bending, stripping and so on show that the prepared Cu/Al clad strip with good quality, good mechanical synergy and peel strength to 12.13N/mm, to meet the requirements of industrial applications.In order to reveal the bonding mechanism of Cu/Al clad strip solid-liquid cast rolling. Based on MSC.MARC and its secondary development technology, establishing Cu/Al clad strip solid-liquid cast rolling bonding area thermo mechanical coupling model, and obtaining evolution rules of temperature and contact pressure, At the same time, sliced samples of the workpiece in the cast-rolling bonding area are acquired through emergency stop and quick cooling, and then Cu/Al interface of the cast rolling area are analysed by scanning electron microscopy(SEM), and energy dispersive X-ray spectrometry(EDS). The result shows that, At the early stage of bonding process, diffusion layer of about 10μm can be obtained as the Cu reacts with Al in the high temperature, and then diffusion layer becomes about 5μm under the continuously pressure. The final bonding is composed of α(Al)+Cu Al2, Cu/Al and Cu9Al4. The result of fracture under scanning electron microscopy(SEM) and X-ray diffractometry(XRD) shows that the dimple is obviousand the location of fracture mostly distribute in aluminium substrate, and the thin and homogeneous interface play the role of reinforcement, getting a well bonded interface.In addition, this paper through to open holes on the surface of the casting roller and combine the two rollers form a closed pass way, to explore the single metal variable section cast rolling forming technology and double metal composite profiles solid-liquid cast rolling clad forming technology feasibility. The experiment has reached the expected requirements, realizing another breakthrough on near net forming technology of simple shaped cross section material forming.