Effect of cold-rolling and annealing on interfacial structures and properties of A500/steel bimetal strip
(Key Laboratory of Electromagnetic Processing of Material, Ministry of Education, Northeastern University, Shenyang 110004, China)
Abstract: The effect of cold-rolling, by both a series of small passes and single-pass with different deformations as well as the subsequent annealing, on the interfacial structures and properties of A500(AlSn8Pb2Si2.5Cu0.8Cr0.2)/steel bimetal strip produced by liquid-solid roll cladding was investigated. Experimental results of the cold-rolling by a series of small passes show that the interfacial bonding strength increases slightly when the total deformation is less than 7.32% and then decreases gradually with the increase in deformation. Subsequent annealing has no effect on the interfacial structures and properties. The effect of cold-rolling by single-pass less than 33.2% deformation on the interfacial structures and properties is the same as that of multi-pass cold-rolling, whereas cold-rolling by single-pass more than 33.2% deformation followed by annealing at 350℃ for 2.5h can make the interfacial bonding strength increase to a great extent. Metallographic examination of the interface shows that there exist only transverse cracks within the interfacial layer and the clad strip does not split along the interface during cold-rolling if the thickness of interfacial layer is less than 4-5μm. The thick interfacial layer(＞5-6μm), however, crumbles during cold-rolling, thus resulting in the splitting of the clad strip.
Key words: liquid-solid roll cladding; bimetal bearing strip; interface; interfacial bonding strength