Influence of Hydrostatic Pressure on FLDs for AZ31B Sheets

Sheet metal formability in terms of the Forming Limit Diagram (FLD) for magnesium alloy AZ31B sheets is studied by using the recently developed Elastic Visco‐Plastic Self‐Consistent (EVPSC) model, in conjunction with the classical M‐K approach. The effect of superimposed hydrostatic pressure on FLDs is numerically assessed. It is found that the superimposed pressure delays the initiation of necking for any strain path. The increment of formability becomes significant when the pressure is larger than about half the initial tensile yield stress of the sheet metal. The difference in predicted FLDs between that with a superimposed hydrostatic pressure and that with a stress component normal to the sheet plane is also discussed.