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Composite rolling characteristics
- Jul 13, 2018 -

Mechanism of metal composite rolling Regarding the mechanism of metal composite rolling, many hypotheses have been proposed by the predecessors, such as "thin film theory" and "diffusion mechanism". "Thin film theory" believes that when cold rolling is compounded, two or more component layer metals will undergo plastic deformation under rolling pressure, resulting in cracking of the composite surface oxide film, revealing a new Benzene metal surface orientation. Contact each other. The atoms of the constituent layer metal reach the lattice constant distance, that is, within the range of the attraction force of the atomic bond, forming a common electronic layer, and the metal of the member is firmly crimped. The "diffusion mechanism" is suitable for hot rolling compounding, which produces plastic deformation at high temperatures, and the metal atoms of the constituent layer obtain sufficient kinetic energy, so that the surface layer atoms are mutually diffused and combined. At the beginning of the deformation, the surface of the contact layer is left with microcracks due to the brushing treatment, and the pure metal is accelerated into the crack, so that the obtained nascent surfaces come into contact with each other to form a nucleation nucleus. As the deformation continues to increase, similar phenomena occur in adjacent contact areas, and the number of nucleation occluded increases until the entire bonding surface is intact.

 

2, the basic conditions of composite rolling composite rolling to make the component layer metal into a solid whole, regardless of cold rolling or hot rolling, generally must have two of these conditions: (1), before composite rolling, components The bonding surface of the layer shall be a clean Benzene metal, and the blank shall be straight. Since the metal bonding surface of the component layer has an oxide film, oil stain, dirt, non-metallic inclusion or adsorbed gas, etc., it is impossible to form a metal bond or a new phase to the intrinsic metal, and to hinder the diffusion of the essential metal atom or the formation of other bonds. Therefore, before compounding, the surface of the component layer should be cleaned and pretreated; (2) and the necessary binding energy is applied. The component layer metal has a clean intrinsic metal surface and requires the necessary energy to be firmly bonded. The binding energy of the component layer is related to the plasticity, deformation resistance, affinity between atoms, relative deformation and heating temperature of the composite metal. Under normal circumstances, the plasticity and deformation resistance of the metal at the high temperature or the component layer are small, or the affinity between the atoms is large, and the relative deformation is large, and the binding energy required for the composite is small. This makes it easier to combine firmly.