TUBE SPINNABILITY OF AA-2024 AND AA-7075 ALUMINUM-ALLOYS

Tube spinnability is defined as the maximum thickness reduction before either fracture or buckling under the given roller geometry, feed rat e, and the speed of the mandrel during the tube spinning of a metal. T here are two ways employed to experimentally determine the tube spinna bility of the full-annealed and solution-treated AA 2024 and 7075 alum inum alloys. One is to reduce the thickness stepwise to the final thic kness without failure the tube. The other is the one-path spinning wit h continuous reduction in wall thickness of preform from initial to th e final thickness without buckling to determine the achieved maximum r eduction. Using continuous reduction test, the determined macro-spinna bility of full-annealed BA 2024 aluminum alloys is 75% and 7075 alumin um is 74%. Whereas, when examined by scanning electron microscope, the deformation tongue is visible on the outer surface as the thickness r eduction higher above 50% for both full annealed 2024 and 7075 aluminu m alloys. However, for both solution-treated 2024 and 7075 tubes, the spinnability is lower than that of full-annealed conditions. The discr epancy between the reduction test and microscopic spinnability will be discussed in terms of the microstructure and the mechanical propertie s. (C) 1998 Elsevier Science S.A. All rights reserved.