Macro- and micro-surface engineering to improve hot roll bonding of aluminum plate and sheet

Hot roll bonding of aluminum plate and sheet currently is the primary manufacturing method of fuselage skin sheet for aircraft and brazing sheet for automotive applications. Tremendous challenges and opportunities exist to improve quality and productivity of these products. This work explored the effects of macro- and micro-surface engineering on hot roll bonding process. It was found that micro-surface engineering yielded better bonding quality than macro-surface engineering did. The critical surface roughness of the core was about 0.58 μm below which bonding quality in terms of area contact and bonding energy can be significantly improved. However, no marked improvement was observed when the surface roughness was reduced further to 0.03 μm. Also, the oxide layer on the surface of the core and local deformation on the surface of liner played a very important role. Ultrasonic test and roller peel test were employed to assess the bonding strength and quality. The quantitative ultrasonic test results are in good agreement with the roller peel test results.