Predicting forming limit diagrams for AZ31 magnesium alloy and 7050 aluminum alloy by numerical simulation

Abstract

Forming limit diagram (FLD) is the most intuitive method to evaluate and analyze the forming performance of sheet metal, which is widely used in production. To examine the formability of AZ31 magnesium alloy and 7050 aluminum alloy, the simplified bulging models based on the Nakazima experiment are established by ABAQUS finite element (FE) software, and the maximum punch force criterion is adopted as the instability criterion. The forming limit diagrams of 7050 high-strength aluminum alloy at room temperature and AZ31 magnesium alloy at warm working conditions are obtained by extracting the in-plane strain of the adjacent element of the maximum strain element at the moment of instability. Compared with experimental observation shows that the Nakazima virtual model established in this paper can accurately predict FLD. In addition, the influences of lubrication conditions and virtual punching speeds on the bulging process of AZ31 and AA7050 sheet metals are also investigated. The results show that the better the lubrication environment, or the lower the punching speed, the better the formability of the sheet, and reducing the punching speed has a more significant improvement effect on the formability of AZ31 sheets.

The Effect of Preheating Temperature on the Forming Limit Diagram of AA1050/AA7050 Al Multilayered Sheets Produced by Accumulative Roll Bonding (ARB)

“…The AA7050 Al alloy presents relatively lower formability at room temperature with FLD o close to 0.06–0.13, as examined by Xue et al [ 31 ] by numerical simulations and Pishyar et al [ 39 ] using Nakazima‐type tests. In the present work, the multilayered sheets roll bonded at 500 °C presented an FDL o of 0.11 (see Figure 6), which is in the range of formability for monolithic AA7050 sheets after artificial aging or overaging.…”

“…The FLD plots for monolithic sheets were added for the sake of comparison in Figure 6. [24,31] Figure 7 shows the broken specimens after Nakazima tests, showing that fractures were located along the dome apex as the lubrication system was efficient.…”

Generalized phenomenological model to analyze the forming limit curve of Al 1050

“…This interesting approach yielded a good agreement with the experimental measurements. A similar approach is adopted by Xue et al 11 with the difference that maximum punch force is adopted as the criterion to indicate the onset of instability. These works are beneficial in that no preexisting flaw is introduced in the initial configuration of the specimen, whether geometrically or by weaker material properties, as opposed to other works.…”