Abstract
The orientation effect of AZ31 alloy sheets prepared by continuous variable cross-section direct extrusion (CVCDE) on corrosion properties was studied by electrochemical methods. The results show that after CVCDE, the uniformity of magnesium alloy sheet in different directions is different, the grains in the extrusion direction (ED) are more fine and uniform, and the crystal planes in the sheet plane perpendicular to different directions are different. Due to the deflection of the basal and pyramidal plane towards the compression direction, the main crystal planes in the plane perpendicular to transverse direction (TD) are (0002), while the crystal planes perpendicular to ED are (1010) and (1120). In electrochemical impedance spectroscopy, the curve can be divided into two stages with time: the gradual formation of the corrosion film and the thickness of the corrosion layer. The thickness of the corrosion layer is an important factor causing the difference of corrosion properties in different directions. Corrosion in different directions begins with filiform corrosion and gradually develops into crevice corrosion and pitting. The (0002) crystal plane perpendicular to TD is easier to form pitting corrosion than the (1010) and (1120) crystal planes perpendicular to ED.

Key words
AZ31 magnesium alloy, sheet, electrochemistry, continuous variable cross-section direct extrusion (CVCDE), corrosion resistance

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