Effect of heat treatment on bond characteristics of aluminium clad steel: Production and characteristics of vacuum roll bonded clad materials (2nd Report)

Abstract

Summary This paper describes production of aluminium clad steel by vacuum roll bonding. The clad steel was heated at 560–650 °C × 0–20 sec to study the formation of intermetallic phases and the shear strength in the bond interface subjected to welding thermal cycles. The results obtained may be summarised as follows: Even under rapid heating at a temperature just under the melting point of aluminium, no intermetallic phases are formed in the bond interface of aluminium clad steel unless there is holding at this temperature. The intermetallic phases formed in the bond interface are FeAl3 and Fe2Al5. The activation energy of their formation is 41 kcal/mol. Even under rapid heating at a temperature just under the melting point of aluminium, the bond shear strength is the same as that of the as‐welded material unless there is holding at this temperature. The bond shear strength depends on the heating temperature and holding time, sharply decreasing under short‐term holding with a rising heating temperature and gently decreasing with a falling heating temperature. The bond shear strength sharply decreases to less than 20 MPa at an intermetallic phase thickness of around > 1.5 μn.