At room temperature, two-pass cold rolling of hot extruded 5A02 aluminum alloy tubes were processed with four different process parameters(A-D). Billets with size of 65.5 mm×5.5 mm (outer diameter * wall thickness, same below) were cold rolled into tubes with size of 58 mm×2.5 mm, with a total reduction of 57.6%.The reduction (%)of first and second pass cold rolling was as following respectively:A(20.2%,47.3%), B(34.4%,35.9%), C(43.6%,25.4%), D(52.7%,11.1%). After each pass of rolling, the tubes were fully annealed at 410℃/1 h. To figure out effect of cold rolling reduction on microstructure and properties of 5A02 aluminum alloy tubes, themicrostructure, mechanical properties, and tensile fracture morphology of cold-rolled tubes were observed and analyzed by means of metallographic microscope, scanning electron microscope("SEM"),energy spectrometer and electronic universal testing machine.The results are as below:for A-D, after the first cold rolling, grain size and second phase become smaller gradually, while tensile strength and breaking elongation become larger gradually; for D, after the second cold rolling, grain size is smallest within 15-55 μm, tensile strength is 186 MPa,and breaking elongation is 29%; for A-D, after the second cold rolling, second phase is the same in size and distribution. The above results show that:with the reduction of cold rolling becomes largergradually, grain size of the tubes become smaller and mechanical properties become better; under the circumstance that total rolling reduction keeps the same, after cold rolling with large reduction in single pass, the grain of the annealed tubes is smaller and more uniform, and its mechanical properties are better; the size of the second phase particles decreases with the increase of cold rolling reduction, and under the circumstance that total rolling reduction keeps the same,the size of the second phase keeps the same as well. © 2019, Materials Review Magazine. All right reserved.
