Constitutive behavior and fracture of intermetallic compound layer in bimetallic composite materials: Modeling and application to bimetal forming process

Abstract This paper presents a novel experimental and computational methodology to characterize the fracture behavior of the intermetallic bonding layer particularly for the bimetallic forming applications. The proposed methodology was applied to Al-Sn bearing alloy/mild steel bimetallic composite. Tensile-shear bimetal samples were fabricated to test the metallurgical bonding layer under shear conditions. Based on the macroscopic behavior, the coupled elasto-plasticity and damage constitutive equations for the bond material were formulated and implemented. The used damage model is written within the framework of the thermodynamic of irreversible processes with the concept of internal state variables and the framework of continuum damage mechanics (CDM). The characterization of the shear fracture behavior of the bond has included FE numerical simulation of tensile-shear tests of the bimetallic composites using ABAQUS/Explicit® FE code with the specially developed VUMAT subroutine. Accordingly, a calibration approach has been proposed to identify the fracture parameters of the bond based on the correspondence between the numerically predicted and experimental global shear force-displacement responses. These parameters have been applied to FE model of the U-bending testing of Al-Sn/mild steel bimetallic composite. A qualitative correspondence between numerically predicted results and U-bending experiment of the bimetal conducted under high-speed camera is deemed extremely satisfactory.