Influence of tension-compression asymmetry on the mechanical behavior of AZ31B magnesium alloy sheets in bending

Kurzfassung

This study investigates the mechanical properties of twin-roll cast-rolled and annealed magnesium alloy AZ31B-O sheet in tension, compression and three-point bending, and the relationship between the mechanical properties and microstructure and crystallographic texture. A new testing method for monotonic in-plane uniaxial compression of thin-sheet magnesium alloys was developed using a grooved thin-sheet specimen. Significant tension-compression asymmetry in terms of strength and strain hardening was observed due to the non-basal slip mechanism in tension and twinning mechanism in compression. The material exhibits much lower yield strength but a much higher strain hardening rate in compression than in tension. The flow stress and accumulative r-value decreases as the loading axis rotates from the rolling direction to the transverse direction because the basal pole of the material slightly spreads along the transverse direction. Moreover, the material exhibits considerable evolution of the r-values in both tension and compression. The bending test results indicates that magnesium AZ31B-O has significantly higher specific energy absorption than mild steel DC04 and stainless steel EN1.4301 and aluminium AW-5083-O, but slightly lower than aluminium AW-6082-T6 in bending. The magnesium AZ31B-O specimens deformed with a larger radius of curvature than the steel and aluminium specimens. It was found that the large radius of curvature for magnesium AZ31B-O is associated with its high strain hardening rate in compression and the strength difference between tension and compression.