Study On Fabrication And Deformation Mechanism Of If Steel-Al Laminated Composite Sheets

In order to study the deformation behavior of laminated metal composites, in this paper layered IF steel- Al composites was fabricated by hot-pressing and hot- rolling technology. Microstructure and interface structure of IF steel- Al was observed by using scanning electron microscope and transmission electron microscope. Different systems of layered metal composites were evaluated by tensile test at room temperature. Deformation of layered IF steel- Al composites under different strain state was investigated with in- situ tensile based on optical microscope experiment.Layered IF steel- Al composites with thickness ratio of 1:1, 2:1, 4:1 and 8:1 of IF steel and pure Al layer were fabricated by hot-pressing and hot-rolling technique. The influence of the thickness reduction of the laminated IF steel- Al composites on mechanis m of the layered composites was analyzed. Layered IF steel- Al composites with different rolling deformation were finally fabricated by changing the rolling deformation. The rolled IF steel- Al composites than were tested by tensile test at room temperature. We got optimal parameters through analyzing the influence of thickness reduction on the mechanical property of composite materials; The influence of the rolling technology on c omprehensive performace of the composite materials was analyzed through observation of the interface reaction and mechnical properties. Based on the in-situ tensile test, the deformation behaviors of rolled IF steel- Al composites with thickness ratio of 1:1 and 8:1 respectively were investigated.Layered IF steel- Al composites in hot-pressing state was fabricated by using hot-pressing and hot-rolling technology. By changing the rolling deformation, we got the layered IF steel- Al composites in hot- rolling state with the deformation of 25%,32% and 40%. The hot-pressing process: heating temperature was 500 oC and kept the temperature for one hour; rolling technology: annealing temperature was 500 oC and held the temperature for 10 minutes.The microstructure of hot-pressed layered IF steel- Al composites with different thickness ratio of IF steel and Al was observed by useing SEM. Then we found the uinform layer thickness, flat interface, well conbined interface and no rolling crack phenomenon. With the growth of the rolling deformation and the times of rolling process, finally the thickness of the interfacial reaction layer in composites increased gradually.Compared with the hot-pressed layered IF steel- Al composites, the yield strength and tensile strength of the layered composites were both improved. With the increase of rolling deformation, the thickness of the interface of the composites increased as well. When the rolling reduction was 32%, the mechanical properties of the composites was the best. From the tensile fracture morphology of the composites, we can observed a large number of equally axial dimple patterns in IF steel layer and vis ible tearing ridge in Al layer, the fracture mode of which was typically ductile fracture.The deformation behavior of laminated IF steel- Al composites was analyzed based on the in situ tensile and other experiments. When the composites was loaded, cracks first appeared in the intermetallic compound layer of the laminated composites. With the load increasing, the cracks in the intermetallic compound layer began to expended. The aluminum layer began to form microcrack and yie ld when the stress at the crack tip in the intermetallic compound layer reached the yield strength of aluminum. With load continued to increase, the cracks in the intermetallic layer expended throughout the entire interface, while cracks in aluminum layer bean extended. At the same time the IF steel layer was no longer limited by interface and it started to appeared cracks. Finall the composites failured with extension of cracks in the IF steel layer.