Numerical simulation of residual thermal stresses in AA7050 alloy during DC-casting using ALSIM5

Conference paper (2010)
Department
Materials Science & Engineering (Mechanical, Maritime and Materials Engineering) (TU Delft)
Copyright: © 2010 Lalpoor, M.; Eskin, D.G.; Katgerman, L.
DC-casting Aluminum alloys Thermal stresses Numerical simulation
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Published Date

07-11-2010

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THERMEC 2009: 6th International Conference on Processing and Manufacturing of Advanced Materials, 25 - 29 August 2009, Berlin, Germany

Faculty

Mechanical, Maritime and Materials Engineering

Department

Materials Science & Engineering

Abstract

Non-homogenous cooling rates and solidification conditions during DC-casting of high strength aluminum alloys result in the formation and accumulation of residual thermal stresses with different signs and magnitudes in different locations of the billet. Rapid propagation of microcracks in the presence of thermal stresses can lead to catastrophic failure in the solid state, which is called cold cracking. Numerical models can simulate the thermomechanical behavior of an ingot during casting and after solidification and reveal the critical cooling conditions that result in catastrophic failure, provided that the constitutive parameters of the material represent genuine ascast properties. Simulation of residual thermal stresses of an AA7050 alloy during DC-casting by means of ALSIM5 showed that in the steady-state conditions large compressive stresses formed near the surface of the billet in the circumferential direction. Stresses changed sign on moving towards the centre of the billet and became tensile with high magnitudes in radial and transverse directions, which made the alloy prone to hot and cold cracking.