AL 2024-T4 alaşiminin nakajima testi ile elde edilen şekillendirme sinir eʇrisinin minimum majör deʇerinin ötelenme nedenlerinin incelenmesi

In a typical forming limit curve (FLC), the minimum major strain where the minor value is equal to zero is located at y axes. In many forming processes, failure occurs at this region. Many studies in literature indicates that minimum major strain value is obtained about at y axis. In this study, the minimum major strain value is not determined on the y axes and it was found to be offsetted from the y axes to the right about 0.04 strain for AA 2024-T4. This value could be important for evaluations of sheet metal forming processes. In this study, the reasons for the minimum major strain of setting of the forming limit curve for AA 2024-T4 were investigated. It was found that drawbead and heat treatment were most effective parameters for this offsetting. It is observed that offsetting result from pre-strain which occur for conducted tests with using draw-bead and residual stress arising from T4 heat treatment.