Effects of temperature, initial conditions, and roller path on hot spinnability of AZ31 alloy.

In the present work, effects of the hot spinning process on the spinnability of AZ31 blank to a tubular shape are investigated. The hot spinning process was carried out by an electrical heating system embedded inside the mandrel. Based on the results, the hot spinning below 250 °C led to fracture. At 250 °C, although deformation imposed no fracture, localized thinning limited the spinnability of the alloy. The spinnability was, however, quite well at the temperature range of 300–450 °C. At this range of temperature, it was found that despite different initial microstructures, the initial conditions of the material, i.e., annealing and as-received conditions, have no significant effect on the spinnability. This was attributed to the complete dynamic recrystallization above 300 °C. Regarding the roller path, two paths of linear and nonlinear paths were implemented. The results show that the nonlinear path of the roller failed to produce a sound tube even above 300 °C. Finite element simulations in combination with a ductile fracture criterion were employed to analyze the low spinnability of the AZ31 blank through this path. Based on the results, this path introduces higher longitudinal strain along with the combination of intensive tensile hydrostatic and longitudinal stresses within the workpiece wall. Such deformation conditions, therefore, cause circumferential cracks at the workpiece wall. [ABSTRACT FROM AUTHOR]