Interfacial Bonding Mechanism Ofaluminium and Steel Composites

The research on singular material is gradually converted to composite material which serves to rectify weaknesses possessed by each constituent when it exists alone. Experiments on Al-alloy 4A60 and 08Al steel plate compounded by cold roll bonding were conducted to analyze the bonding mechanism of the interface during the composite process of laminated metal. SEM, EDS, and laser confocal microscope were used to observe the interface and section of composites while the bonding strength was tested by universal tensile machine. The result showed that bonded metal's surface microtopography, reduction and diffusion annealing were the most critical influences on the bonding of composites, and the roll bonding mechanism of 4A60/08Al composite was divided into three stages: 1) Physical contact. Two component layers were mechanically occluded by the rolling pressure, the bonding strength was low; 2) Metallic bonding. The oxide layer and the hardened layer covered on the metal surface break which made the two component fresh metals to full contact, chemical action happened and metallic bonding formed when the interatomic distance reached a certain stage, the bonding strength increased; 3) Metallurgical bonding. In the subsequent annealing treatment, the bonding strength significantly increased because the diffusion of metal atoms at the interface.