Effects of Wavy Roll-Forming on Textures in AZ31B Magnesium Alloy

Abstract

A new technique has been developed for randomizing the basal plane texture formed by rolling or extruding deformation in a magnesium alloy. Specimens are roll-formed using rolls having wavy surfaces at elevated temperatures. This technique has been applied to specimens of AZ31B magnesium alloy sheet. The specimens were heated at 623 K and 723 K for 300 s, and then immediately wavy roll-formed. This process was repeated 8 times, rotating the specimen at 90 degrees for each subsequent pass. The specimen showed a typical basal plane texture before the wavy roll-forming, and the texture was randomized after the treatment. Annealing at 573 K and 673 K, and/or flat-rolling at 623 K on the wavy roll-formed specimen caused a reversion to the basal plane texture. Transmission electron microscopic observations on the wavy roll-formed specimen showed dislocation substructures consisting of many twins and dense dislocations, which resembled those formed by conventional flat-rolling. Randomizing would occur by macroscopic mechanism, such as lattice rotation due to wavy form deformation.