Project Details
Projekt
Model-based description of bond formation, evolution and failure in multi-pass roll bonding processes
Applicant
Professor Dr.-Ing. Gerhard Hirt
Subject Area
Primary Shaping and Reshaping Technology, Additive Manufacturing
Term
from 2016 to 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 317614920
In the context of the preceding project, a laboratory experiment to analyze the bond formation and to subsequently characterize the bond strength was developed. The results of the laboratory experiments were then used to calibrate a user-subroutine (UINTER) for the material combination AA1050/AA2024. Based on simulations of single roll bonding passes - using the UINTER based modelling approach - the experimentally observed separation of the bond during the rolling process could be qualitatively confirmed. Within this project the next step will be the further development of the characterization and modelling method towards a description of multi-pass roll bonding processes as well as the model validation. The material combination AA6016/AA8079 which cannot be processed industrial at the moment but is of great interest for usage in the automobile manufacturing is to be investigated. The core made of AA6016 is a standard precipitation-hardening aluminum alloy and the surface layer made of AA8079 is a nearly pure aluminum alloy with small quantities of iron and silicon. This results in a high formability and corrosion resistance. To analyze multi-pass roll bonding processes, in particular the temperature evolution in the material and the effect of diffusion in between the rolling passes has to be characterized and taken into account during the modelling. Furthermore, the higher accumulated deformation and the interpass times between the rolling passes require improvements in the numerical stability of the solution algorithm. Therefore, the objectives of the present knowledge transfer project are: 1) Characterization of a parameter field to calibrate the user-subroutine (UINTER) for the investigated material combination (AA6016/AA8079) based on the laboratory experiment developed in the previous project. 2) Additional development of a multi-step laboratory experiments to characterize the influence of diffusion in between the rolling passes, for a detailed description of the evolution of bond strength. 3) Improvement of the process- and bonding model to describe and analyze reversing or continues multi-pass roll bonding processes. - Regarding the bonding model this requires the description of the bond strength evolution during forming and in the interpass times. - Regarding the process model the heat exchange with the surrounding and the rolls has to be considered. Additional, if the single pass deformations in the process degradate the mesh the bond strength needs to be transferred to a new mesh for the next pass. 4) Validation of the improved process and bonding model by comparison of the results with rolling experiments conducted on the laboratory rolling mill of the project partner.
DFG Programme
Research Grants (Transfer Project)
