Magnesium Alloys AZ31B Sheet Bulging Test And The Formability Research

Magnesium alloy is known as one of the green engineering materials in21st century. It has lower density, therefore its products are light, and have lower energy consumption. Besides, magnesium alloy has special strength and stiffness, along with good machining property and casting performance. The formability of magnesium alloys is very good at a high forming temperature. With many kinds of plastic forming, it can be processed into sheets, rods, profiles and powder materials, as well as castings, forgings and die forgings.The plastic formability of magnesium alloy sheets is concerned with forming temperature, velocity, the thickness of the sheet, and the friction between the mold and the sheets. In this paper, the Limited Dome height Test is used to explore the impact of forming parameters on the formability of magnesium alloy sheet, resulting in finding the optimum method to raise the forming ability.(1) In the forming temperature range from100℃to250℃, the formability is gradually increasing with the rising of temperature.(2) When the thickness of the sheet is0.6mm, the formability is optimal. As the thickness of the sheet is lower than0.6mm, the formability is improved with the increasing of thickness; reversely, the formability is lessened with the increasing of thickness.(3) Comparing the two forming velocities of10mm/min and1mm/min, a lower velocity can improve both limited dome height and bulging coefficient, but it is not suitable for wide application in industrial production.(4) The formability is always better when the sheet is lubricated by some lubricants such as MoS2than that without lubrication.On the other hand, a steps-forming method is presented in this paper.(1)This new method is compared with the single-forming method; the formability of sheet metal has slight increase by steps-forming method than that of the single-forming method.(2)The impact of performing height and soaking on steps-formability is analyzed. The limited dome height and bulging coefficient are chose to analyze the formability. When the performing dome height is10mm, the soaking is1h, the formability is great, its limited dome height is42mm, and its bulging coefficient is1.000.(3)The microscopic grain structure of the direction that is perpendicular to bulging direction under all kinds of condition and the undeformed part of the sheet is observed, and the impact of steps-forming method on the formability of magnesium alloy sheet is analyzed from the view of internal mechanism:when the steps-forming method is used, the grain of undeformed part of the sheet has a certain extent compared to the original sheet; the grain of dome side wall has recrystallization under different performing dome height and different soaking; when the performing dome height is10mm, the soaking is1h, the sheet completes recrystallization, the grain microscopic average intercept of the direction that perpendicular to the bulging direction is17.0μm.