Tube spinnability of AA 2024 and 7075 aluminum alloys

Tube spinnability is defined as the maximum thickness reduction before either fracture or buckling under the given roller geometry, feed rate, and the speed of the mandrel during the tube spinning of a metal. There are two ways employed to experimentally determine the tube spinnability of the full-annealed and solution-treated AA 2024 and 7075 aluminum alloys. One is to reduce the thickness stepwise to the final thickness without failure the tube. The other is the one-path spinning with continuous reduction in wall thickness of preform from initial to the final thickness without buckling to determine the achieved maximum reduction. Using continuous reduction test, the determined macro-spinnability of full-annealed AA 2024 aluminum alloys is 75% and 7075 aluminum is 74%. Whereas, when examined by scanning electron microscope, the deformation tongue is visible on the outer surface as the thickness reduction higher above 50% for both full annealed 2024 and 7075 aluminum alloys. However, for both solution-treated 2024 and 7075 tubes, the spinnability is lower than that of full-annealed conditions. The discrepancy between the reduction test and microscopic spinnability will be discussed in terms of the micro structure and the mechanical properties.