Numerical Determination of the Forming Limit Diagram for 304 Stainless Steel Based on Phase Change in Deep Drawing Process

Up to now a large number of models have been developed to measure or predict the damage in equipments. Some of these models have been implemented in ABAQUS software. To implement damage parameters in the software, it is necessary to perform complex and expensive practical tests. One of these damage models is Forming Limit Diagram (FLD).The purpose of this research is deriving required parameters for modeling damage by numerical method and using of software. To study and compare of the accuracy of this method, these parameters have been derived with experimental method. FLD parameters for metastable austenitic stainless steel 304 have been extracted from Erichsen test and then phase change from austenite to martensite during deep drawing have been modeled with CLEMEX and SIGMAPLOT software. By defining changes of physical and mechanical properties of elastic-plastic material, the obtained results are transmitted to ABAQUS via developing a VUMAT subroutine in FORTRAN. Then Erichsen test has been simulated in ABAQUS and aforementioned subroutine was used to define changes of properties in simulation. Critical points susceptible for necking in all test cups are determined and numerical FLD was drawn based on principal strains in these points. Finally, the results of this method and practical tests were compared