Research On The Rolling Bonding Mechanism And The Growth Behavior Of Intermetallic Compounds At Aluminum Steel Composites Interface

With the progress of science and technology,as well as the country's strong support for the field of new materials,the original single metal can not meet the requirements of the industry,composite materials have been rapidly developed in the area of manufacture and scientific research.Aluminum-steel(Al-St.)composites are a new kind of metal laminated composites,it has not only high strength,good corrosion resistant and beautiful surface characteristics of steel,but also light weight,good ductility,good thermal conductivity and other characteristics of aluminum.So,Al-St.composites are applied to more fields than the original single metal.At the same time,a large number of researchers have been attracted to the research of Al-St.composites.However,most of the researchers at home and abroad have focused on the study of the microstructure and properties of the composites and the process parameters of production.It is of great significance to investigate the bonding mechanism of Al-St.composites,which is benefit to further reveal and understand the bonding behavior of composite materials and provide theoretical basis for the production.In order to investigate the bonding mechanism of Al-St.composites,aluminum 4A60 and steel 08 Al were selected as rolling materials and bonded by cold rolling.The bonding mechanism and growth behavior of intermetallic compounds at Al-St.composites interface were detected and analyzed by various experimental instruments and equipment:surface profiler machine,super depth machine,X-ray diffraction(XRD),optical microscope(OM),scanning electron microscopy(SEM),energy dispersive spectroscopy(EDS),universal testing machine and nano probe and so on.Systematicly studied the cold rolling bonding behavior of Al-St.composites,revealed the rolling bonding mechanism of Al-St.composites,analyzed the effects of intermetallic compounds(IMC)in the annealing process on the bonding properties of Al-St.composites interface,and explored the growth behavior and the growth kinetics of IMC at Al-St.composites interface.Specific research contents and results are as follows:In the rolling process,to investigate rolling bonding behaviors of Al-St.composites and build the interface bonding mechanism model,the surface of steel layer was prepared by different methods.The research carried out from four aspects that were reduction,degree of work hardening,surface morphology and surface oxidation on the steel layer.Then,this paper analyzed the evolution of the morphology of Al-St.composites interface and the peeled surface of Al-St.composites,and explored the rolling bonding behavior.The results show that in the rolling process,first the work hardening layer and the oxide layer covered on the steel surface rupture under the force of reduction,then internal non-oxidation fresh metal of steel layer exposes and the opposite soft aluminum press into the cracks to form mechanical bite.When the pressure become large enough,the pressed aluminum combine with the internal non-oxidation fresh metal of steel layer to form a stable bonding.It found that Al-St.composites interface generated brittle IMC in the annealing process,which seriously influenced on the bonding.So this paper studied the growth behavior and the growth kinetics of IMC on Al-St.composites interface in the annealing process.The results show that the growth law of the IMC is in accordance with the parabolic characteristics,and the thickness of the IMC increases with the increase of the annealing temperature or the holding time.Besides,when the thickness of the IMC is more than 9 ?m,the interface bonding strength decreases sharply.