Influence Of Initial Orientation On The Plastic Behavior Of AZ31Magnesium Alloy Under Uniaxial Tension

In the present study, the hot-rolled commercial wrought magnesium alloy AZ31has been investigated by uniaxial tension at temperature range from RT³00℃, withstrain rate from0.0005⁰.01s^-1. In order to investigate the effect of initial texture onthermal deformation behavior, three samples are cut through normal direction（ND）,rolling direction（RD）,45°inclined to normal direction in ND-RD plane（45）,respectively. The effect of temperature, strain rate and initial texture on the mechanicalbehavior were systematically analyzed, the microstructure evolution of the deformedspecimens has been studied by using Optical Microscopy（OM） and ElectronBackscatter Diffraction（EBSD）. The relationship between deformation mechanism anddynamic recrystallizaiton （DRX） ware explored and the correlation with mechanicalbehavior and microstructure was clarified in detail. The main conclusions found are asfollows：①Iinitial orientation has an impact on mechanical behavior below250℃. Alow yield point was observed in ND and45samples. Strain hardening behavioroccurred during the subsequent deformation. The hardening rate of45samples is lowerthan ND sample’s. The value of σ0.2in RD sample is nearly three times of the othertwo samples’.â‘¡Plastic anisotropy of AZ31magnesium alloy was observed whendeformed below250℃, and decreased with increasing temperature. At300℃，itbecame almost isotropic.â‘¢The initial orientation has a significant influence ondeformation mechanism. ND sample favors the tension twinning while RD sample isunfavorable for tension twining, neither basal slip; the main deformation mechanism of45samples are basal slip and tension twinning. The amount of tension twin occurred inND and45samples are responsible for low yield point and strain hardeningphenomenon, while basal slip resulted the lowest flow stress in45sample.â‘£DRXwas happened when deformed above250℃in this paper, the nucleation location ofND sample is complex while bulging DRX nucleation is obsvered in RD and45samples.⑤Compared with45and RD samples, ND sample has the highest volumefraction of DRX grains and smaller DRX-grain size，which should be attributed tolarge number of tension twin occurred at the initial stage of the deformation at300℃.The orientation distribution of DRX grains in ND sample is random,while in45andRD sample’s are similar to the matrix, this should attributed to the different deformation mechanisms activated in three samples.