Experiment and computation: A combined approach to characterize the constitutive and fracture behaviors of metallurgical bonding interface in bimetallic composites

Abstract

This paper presents a novel experimental and computational approach to characterize fracture behavior of the intermetallic bonding layer (IMBL) in bimetallic bearing materials. The proposed methodology is applied to tin (Sn) based Babbitt alloy/mild steel bimetallic composite. In this study, macro stress–strain behavior of the bond under tensile-shear stress was calculated by considering the local shear surface geometry instead of the apparent bonding zone. The metallurgical bonding layer failure mechanism was identified from the scanning electron microscope (SEM) observations of the fractured IMBL of the bimetallic samples tested in tension-shear. It has been found that a damage mechanism of ductile nature was the cause of tearing of the IMBL. The coupled elasto-plasticity and damage constitutive equations for the IMBL were formulated and implemented based on SEM observations. Characterization of the shear fracture behavior of IMBL included FE numerical simulation of tensile-shear tests of the bimetallic composites. Consequently, a calibration methodology is proposed to estimate the IMBL fracture parameters. This proposed approach validation was based on a qualitative and quantitative confrontation between the experimentally measured shear force-displacement diagram and the numerically calculated diagrams obtained from the simulated IMBL. Commendable average quantitative errors of almost 1% are achieved in terms of yield strength, ultimate strength, and elongation at break between computed results obtained within sheared regions of the simulated Babbitt/steel (Sn – IMCs) BL and experience. The results of such a confrontation are promising for the application of the proposed approach to predict fracture during the forming of bimetallic composite materials.