Interfacial Reaction on Heat Treatment of Roll-bonded STS304/Al1050/STS439 Clad Materials and its Effect on the Mechanical Properties

The microstructures and mechanical properties of roll-bonded STS439/Al1050/STS304 clad materials were investigated after an annealing process at various temperatures. Interfacial layer was developed at the STS439/Al1050 and Al1050/ STS304 interfaces at 550°C. STS439/Al1050/STS304 clad metals fractured suddenly in a single step and the fracture decreased with increasing annealing temperatures at 45 °C. After annealing at 550°C, samples fractured in three steps with each layer fracturing independently. Interfacial layers formed at 550°C with a high Vickers microhardness were found to be brittle. During tensile testing, periodic parallel cracks were observed at the interfacial reaction layer. Observed micro-void between Al1050 and the interfacial layer was found to weaken the Al1050/reaction layer interface, leading to the total separation between Al1050 and the reaction layer.