Effect of Bending-Tension Deformation on Texture Evolution and Room Temperature Formability of AZ31 Alloy Sheet Rolled at High Temperature

Abstract

Bending – tension deformations were conducted to AZ31B ( Mg – 3mass ％ Al – 1mass ％ Zn ) alloy sheets with weak basal texture intensity and RD ( rolling direction ) – split texture, which were processed by high – temperature rolling. E ff ects of process pass number of bending – tension deformation on the texture formation and related room temperature formability were investigated. 1 pass bending – tension deformation contributed to signi fi cant increase in the RD – split angle from 13 ° to 25 ° , and additional bending – tension deformation only contributed to slight increase in the RD – split angle. 7 pass bending – tension deformation increased basal texture intensity from 2.9 to about 4.5, which was still much lower than those of commercial AZ31B alloy sheets. Specimens subjected to less than 5 pass bending – tension deformations kept signi fi cant stretch formability ( 8.0mm of Erichsen value ) . However, specimens subjected to 7 pass bending – tension deformation exhibited deteriorated Erichsen value of 6.7mm regardless of the high RD – split angle, low basal texture intensity and high average Schmid factor. As a result of microstructural observation, it was revealed that repetition of bending – tension deformation generated area with coarse grains at near surface. In addition, repetition of bending – tension deformation induced duplex microstructure at the surface, where layers of fi ne grains and coarse grains were distributed along to the RD on the RD – TD ( transverse direction ) plane. It was suggested that the above microstructural changes induced inhomogeneous deformation at grain boundaries and in double twinning, resulting in the deterioration of the stretch formability of the specimens subjected to 7 pass bending – tension deformation. ［ doi:10.2320 / jinstmet.JBW202001 ］