Influence of material modeling on warm forming behavior of nickel based super alloy

The present study helps in providing a systematic approach towards the investigation of deep drawing and stretch forming processes for Inconel 625 alloy. Firstly, the flow stress nature and material properties of Inconel 625 super-alloy have been investigated and it has been found that temperature and deformation rate significantly affects the flow stress behavior. By using experimental flow stress data, four different constitutive models namely; modified Jhonson-Cook (m-JC), modified Zerilli-Armstrong (m-ZA), modified Arrhenius (m-A), Khan-Huang-Liang (KHL) model have been formulated of which m-A has been found to have the best predictability for flow stress. Hill 1948 and Barlat 1989 anisotropic yield criterion have also been applied and it has been found that Barlat 1989 criteria more accurately capture the yielding behavior of Inconel 625 alloy. The deep drawing analysis has been carried out using target and noise performance measures for different process parameters viz., temperature, punch speed and blank holding pressure. Uniformity in thickness has been major cause of concern, hence experiment at 473 K, 5 mm/min speed and 20 Bar pressure was found to have least variation in thickness. Furthermore, the forming limit diagram (FLD) and fracture curve (FC) obtained from stretch forming analysis along five different strain paths was found to be significantly affected by temperature. Further, user defined material (UMAT) subroutine have been incorporated in ABAQUS 6.13 software to have effect of m-A model and Barlat 1989 yield criteria in finite element analysis (FEA) of deep drawing and stretch forming processes.