Influences of tensile pre-strain and bending pre-deflection on bending and tensile behaviors of an extruded AZ31B magnesium alloy

• Tensile tests of magnesium alloy with bending pre-deflection.
• Bending tests of magnesium alloy with tensile pre-strain.
• Hardening behaviors during tensile/bending tests with pre-deflection/strain.
• Improvement of yield stress by bending pre-deflection.

This paper focused on the influences of tensile pre-strain and bending pre-deflection on the three point bending and uniaxial tensile properties of an extruded AZ31B magnesium alloy. The influences of pre-strain/deflection on bending/tensile curves could be divided into three stages. The results show that: (1) In the elastic stage, considering the variation of specimen’s cross sectional area, the pre-strain/deflection did not affect the measured elastic modulus obtained from both bending and tensile tests. (2) In the transition hardening stage, the specimen presented obvious hardening behaviors on basis of the pre-strain/deflection, the phenomenon was mainly caused by the strain hardening effects produced from previous uniaxial tensile and bending processes. (3) In the large plastic deformation stage/necking stage, as the accumulation of plastic deformations caused by pre-strain/deflection were significant, the specimen’s ability to resist plastic deformation was weakened. Specially, as the tensile pre-strain increased, the bending load decrement rate gradually decreased, and as the bending pre-deflection increased, both the tensile strength and elongation sharply decreased, the accumulated irreversible plastic work promoted the damage process of the magnesium alloy. The influences of tensile pre-strain on the bending behaviors of the magnesium alloy were also analyzed via finite element method.