An Investigation Of Deformation Behavior And Bonding Strength Of Bimetal Strip During Cold Rolling

With the development of the modern science and technology, a higher request has been set to the metal material, and the single metal material has not been able to meet the need to development. The material which is bond with different kinds of materials by using the compound cold rolling technology can achieve the request. The compound materials have various capability of ever single-layer material. It can satisfy the market demand, achieve the energy conservation, reduce the cost, display best economic efficiency, thus it's being used extensively in industry domain such as the aviation, chemical industry, automobile, atomic energy and so on. However the cold rolling bonding is a complex technology, therefore the research of the bonding mechanism is extremely essential.A mathematical model for cold rolling of bimetal strip has been established using the Avitzur upper bound theorem to investigate the plastic deformation behavior of the strip. Not only the velocity field, power of deformation and rolling force, but also the thickness ratio of the rolled product have been analyzed, and equations are available for calculate those relevant parameters. Experimentation using the cold rolling bimetal strip of the stainless steel and the aluminum proved the validity of the model, and the influencing factors about the thickness ratio and the bonding strength have been investigated based on this model.The research indicated that, in the rolling process, the thickness ratio of the soft metal thick decreased unceasingly, but the tendency of the decrease was more and more slow. When rolling force couldn't fulfill the equation of power balance, rolling sheets was able to curve at the exit of the rollers. Increasing deformation ratio of the soft metal strip and enhancing friction between the internal surfaces of bimetal strip can increase the precision of the thickness ratio and decrease the curve. It's also discovered that the surface treatment, the total deformation ratio and the annealing temperature have an important influence in bonding strength. Replacing straight burnishing with cross burnishing for the stainless steel, using corroding instead of burnishing for the aluminum, and increasing the total deformation ratio can also increase bonding strength. Meanwhile choosing a proper annealing temperature is also an effective way to increase bonding strength. The experimentation proved that bonding strength increased first and then turned down. It could obtain the best bonding intensity when the annealing temperature was about 420℃.