Formability Prediction of AISI 304 Steel Sheet Based on Forming Limit Diagram through Finite Element Analysis and Nakazima Test

Abstract

In this study, the appropriateness of the forming limit stress diagram and the forming limit diagram for predicting the formability of sheets of AISI 304 steel is compared. The Forming Limit Diagram was plotted using a numerical technique and the Nakazima test. Conversely, Forming limit stress diagram was constructed using the Marciniak - Kuczynski theoretical model based on the principal stresses, and a simulation of the Nakazima test was done using finite element analysis for the same input conditions as applied in the theoretical model. From the cup drawing test, it was identified that the maximum drawing height measured for the experimental cup was 24 mm and the predicted drawing height in finite element simulation for the same blank was nearly 22.38 mm with an error of 7%. Also, it is proved that more deviation was identified between the strain path predicted by finite element studies and the experiment failures of forming a limit diagram by the Nakazima test. Contrasted with forming limit stress diagram predict the crack initiating element accurately by identifying the stress path through finite element studies. The results of this study prove that the stress based forming limit diagram predicts the formability characteristics very well than the strain based forming limit diagram.

Keywords

• forming limit diagram
• aisi 304 steel
• formability
• nakazima test and finite element analysis
• forming limit stress diagram