Research On Hot Rolling And Hot Forming Limit Diagram Of Aluminum Clad Magnesium Sheet

Magnesium alloy is a new kind of environmentally friendly structural material, so it has broad prospects. However, magnesium will be corroded in the open air, which will severely reduce the using value. The new sheet, that is magnesium clad aluminum sheet, will be formed by covering magnesium sheets with antirust aluminum sheets and combining them closely. Thus, the disadvantages of the two kind of materials will be remedied, and the advantages in application fields will be more clear. In order to process this novel sheet into sheet metal for wide use, we should research on the formability of the sheet at first. Formability can be evaluated by measuring limit deformation under different strain states. However, forming limit diagram can express forming limit and evaluate the formability clearly and quantificationally. So discussing the properties of forming limit diagrams at warm state is significant.In this paper, after-rolling annealing process of aluminum clad magnesium slabs is carried out. The result show that the grain of az31magnesium slabs that is annealed at300℃for30min recrystallizing, the grain size is homogeneous and the grain state is fine and the yield strength and the extension strength increase by8.0%and2.2%, and the elongation is16.4%, which is benefit for plastic deformation of aluminum clad magnesium rolling. The result show that the yield strength and the extension strength of the5052aluminum slabs that is annealed at350℃for60min decrease, and the elongation is25%, the plasticity increase greatly, and the yield ratio decrease by48.5%, which is benefit for plastic deformation of aluminum clad magnesium rolling.In this paper, hot rolling forming process and annealing process of aluminum clad magnesium is carried out. The best rolling process is:the first rolling temperature is360℃, the other three temperature is390℃; the first three warming time is15min, the last pass warming temperature is lOmin. The reduction rate is33.53%,30.43%,25.00%,16.67%. After the annealing process of temperature is160℃to220℃and time is30min to120min, the results show that the interface of the rolled sheets form a diffusion layer with a thickness of18.35μm, the thickness increase after annealing; After annealing at180℃for120min, the grain is equiaxial, small and uniformity with the average diameter is5.64μm and the diffusion layer thickness is18.71μm; the yield ratio is0.634and the elongation is17.7%, the comprehensive mechanical property is fine.In this paper, forming limit diagram at the temperature of170℃and230℃is drawed according to the Chinese national standard GB/T15825.8-2008and the influence of strain state and temperature to forming limit diagram is analyzed. The conclusion shows that the uniaxial tension zone of the FLD is higher than the biaxial tension zone at170℃, and the uniaxial tension zone and the biaxial tension zone is nearly the same. With the increase of the temperature, the forming limit of the aluminum clad magnesium increase. The forming limit at230℃is higher than the forming limit at170℃.