Effect of Si on the interfacial bonding strength of Al–Pb alloy strips and hot-dip aluminized steel sheets by hot rolling

Bonding of Al–Pb alloy strips and hot-dipped Al or Al–2% Si steel sheets were carried out using hot rolling. The effects of addition of 2% Si to the bath, the dipping time, the thickness of the intermetallic layers and the fraction of the blank interfaces on the bonding strength are investigated. In all case, two different kinds of interfaces are produced, hot-dip aluminized steel sheets and Al–Pb alloy strips are bonded through the mechanism of blank and block interface bonding. The total bonding strength depends mainly on that of blank interface and the fraction of the blank interfaces. The bonding strength of blank interfaces is four or five times as high as that of block interfaces. There is a linear relationship between the bonding strength and the fraction of the blank interfaces. An EPMA linescan across the blank interface reveals that higher concentration of aluminum in the transition layer of Fe and Al formed in the blank interface region for a dipped specimen of Al–2% Si than that for a dipped specimen of Al.