2006 Volume 24 Issue 3 Pages 215-222
We hold many expectations that aluminum-clad steel will be applied for functional material, structural transition joint for welding steel structure to aluminum structure and so on. In this study we investigated the effects of aluminum purity and/or bonding conditions, which were bonding temperature, reduction rate of aluminum plate thickness (RAl), vacuum degree, on bond tensile strength of aluminum-clad steels produced by the vacuum roll bonding. And also the bond interfaces were observed using a high-resolution transmission electron microscope (RE-TEM).
When A1050/SS400 clad materials, which produced at more than 450°C in bonding temperature, more than 17% in RAl and less than 10 Pa in vacuum degree, were performed in tensile test, they fractured through base metal of the aluminum. The values of bond tensile strength were obtained over 100 MPa. The bond tensile strength of 4N-Al (99.99 mass%Al) /SS400 clad material, which produced at 500°C in bonding temperature, 20% in RAl and 3 Pa in vacuum degree, was obtained about 80 MPa and test piece fractured through base metal of the aluminum. In the analysis results for bond interface of A1050/SS400 clad materials (500°C in bonding temperature, 20% in RAl and 3 and 10 Pa in vacuum degree) using a HR-TEM and an electron dispersive spectroscopy (EDS), no intermetallic compound and continuously amorphous phase in thickness from 2 to 3 nm were observed. The composition of the amorphous phase consists of mostly Al, O, Fe and Si. For the bonding interface of 4N-Al/SS400 clad material (500°C in bonding temperature, 20% in RAl and 3 Pa in vacuum degree), amorphous phase and nano-crystal were observed using HR-TEM. Therefore, it was clarified A1050 and 4N-Al/SS400 clad materials obtained using a vacuum roll bonding were bonded through the amorphous phase.