The EBSD Situ Follow-up Study Of Deformation Mechanism Of Differential Speed Rolling Magnesium Alloysheet

Magnesium and its alloys are the lightest metal structure materials. Magnesium alloys have the lower density, which was about two-thirds of that of aluminum, and a quarter of that of steel, morever, Magnesium alloys have high specific strength and specific stiffness, and they are widely used in aviation, aerospace, automotive, electronics and medical devices manufacturing fields. Up to now, most magnesium alloys structure parts were produced by the die casting technique, but they have more defects and lower strength, resulting in magnesium alloys applications were greatly restricted. Magnesium alloys have poor plastic formablity at room temperature, for the higher temperature deformation of magnesium alloys, in which the cost in was relatively higher, and it was not easily to be implemented. For investigations on the warm forming mechanism and performance improvement of magnesium alloys, it was of great significance for producing the magnesium alloy components. In this paper, the main research contents and results are as follows:(1) The 5 mm and 3 mm thick AZ31 B magnesium alloys sheets were separately used in differential speed rolling(DSR) and asymmetric rolling under different temperatures. The results show that the DSR can weaken basal texture, and grains were significantly refined under conditions of the certain speed ratio(1.2) and pass reduction(20%). The refinement mechanisms of asymmetric rolling(ASR) process at different temperatures were different, for the ASR at 150?, grains were mainly refined by twinning, but for the ASR at 250?, grains were mainly refined by the dynamic recrystallization. The magnesium alloys sheets produced by the ASR at 150? have good mechanical property and formability after annealing by 250?×1h.(2) The 3.3mm thick DSR magnesium alloys sheets were used for the EBSD in-situ tracking experiment. Related studies show that: for grains with angles greater than 60o between grain c-axis and compression axis, they would will rotate 86.3o at the initial phase of radial direction(RD) compression, producing a mass of {101 2} extension twins, the higher the value of Schmid Factor(SF), the greater the possibility of twinning, as is more likely to grow up with deforming. Twinning and basal slip are the main coordination deformation modes. As the temperature raised, twinning activity tends to decrease, pyramidal slips gradually start, the influence of SF on the occurrence and growth of twinning was gradually lowered.(3) The 1.1mm thick ASR magnesium alloys sheets were used in the EBSD in-situ tracking tension experiment.Studies show thatonly basal and prismatic slips activate to coordinate deformation during tension along RD, and more prismatic slips start with the temperature raised.