Quantification of temperature, stress, and strain fields during the start-up phase of direct chill casting process by using a 3D fully coupled thermal and stress model for AA5182 ingots

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 397; no. 1; pp. 157 - 177
• Main Authors: Sengupta, J., Cockcroft, S.L., Maijer, D.M., Larouche, A.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25-04-2005; Elsevier
• Subjects: AA5182 constitutive behavior; AA5182 ingots; Aluminum alloy ingots; Analysing. Testing. Standards; Applied sciences; Burt curl; Coupled heat transfer and heat analysis; Direct chill casting; Exact sciences and technology; Finite element methods; Hot tearing; Ingot base cooling; Metals. Metallurgy; Primary cooling; Residual stress; Ring hole method; Secondary cooling; Start-up phase; Strain measurements; Stress analysis; Water ejection; Water incursion; Ring hole method; Hot tearing; Primary cooling; Finite element methods; Water ejection; Burt curl; Water incursion; Strain measurements; Direct chill casting; Start-up phase; AA5182 constitutive behavior; AA5182 ingots; Ingot base cooling; Coupled heat transfer and heat analysis; Aluminum alloy ingots; Secondary cooling; Residual stress; Thermal stress; Surface temperature; Iron; Boundary condition; Finite element method; Energy gap; Strain distribution; Mathematical model; Ingot; Stress analysis; Cooling; Aluminium; Casting; Stress distribution; Heat transfer
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2005.02.011

A comprehensive coupled thermal-stress mathematical model, based on the commercial finite element (FE) package ABAQUS™,
1
1
ABAQUS is a registered trademark of ABAQUS, Inc., Pawtucket, RI.
has been formulated to describe thermal and stress–strain fields during the start-up phase of the direct chill (DC) casting process for AA5182 aluminum ingots. The computational domain includes industry-scale ingot and bottom block geometries. The heat transfer analysis incorporates the thermal boundary conditions that describe primary cooling via the mold, secondary cooling via the chill water, and ingot base cooling. To quantify the extent of secondary cooling, boiling curves that are a function of ingot surface temperature, water flow rate, impingement point temperature, and position relative to the point of water impingement have been used. Other complex heat transfer phenomena including water ejection on the vertical faces of the ingot, and water incursion into the gap at the base of the ingot have also been accounted for. The stress analysis employs a temperature dependent elastic rate-dependent plastic material constitutive behavior to quantify the stress and strain fields inside the ingot. The model has been validated against temperature and displacement measurements obtained from two 711
mm
×
1680
mm AA5182 ingots, cast under different start-up conditions (non-typical “cold” practice and non-typical “hot” practice). The stress analysis was further validated by residual stress data obtained from the cold cast ingot. Comparison of the model predictions with the industrial and laboratory data indicates that the model is capable of satisfactorily simulating aspects of the thermomechancial behavior of the ingot during the start-up phase. The model has been applied in a preliminary way to analyze the problem of hot tearing in ingots during the startup phase. The need for further refinement of the mesh has been identified.