Hadzic, Semin;Schmidtne Kelity, Edina;Sommitsch, Christof, Prediction and validation of hot tearing in permanent mold steel casting using a viscoplastic damage model

Abstract:

Hot tearing has long been studied by experiment and simulation in many scientific disciplines such as welding, casting of ferrous and nonferrous alloys as well as continuous casting of aluminum or steel. Hot tearing is one of the common defects found in the final cast product. Removing defect areas from the casting followed by welding repairs these defects in steels. Furthermore, pre- and post-weld heat treatment is necessary, leading to extensive procedures and high cost. Generally, theoretical approaches assume that a hot tear forms during solidification at or just above the solidus temperature due to residual liquid films along dendritic interfaces. Porosity can be formed in the last stage of solidification due to shrinkage and may act as a nucleation site for hot tears. The formation of hot tears can also be attributed to insufficient feeding of liquid in the mushy zone and simultaneous thermal and mechanical loading of the dendritic network. This loading, caused by the contraction of the casting and by geometric constraints of the mold, produces thermal and mechanical strains, which causes additional voiding, i.e. damage. Also other parameters such as alloy composition, mechanical properties and cooling history can affect the formation of hot tearing. In this work the calculation of solidification and deformation was done using commercial software with a user-defined constitutive model. The shrinkage porosity information is coupled to the solid deformation constitutive model to calculate the material damage. For this, a viscoplastic model was applied to predict the hot tear formation in permanent mold steel alloy casting. Hot tears are to be expected in region of extensive damage. A good correlation between experimental findings and predicted damage was observed. Keywords: hot tear, casting, steel alloy, viscoplasticity, damage, solidification


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@article(hadz13pred,
author = "Hadzic, Semin;Schmidtne Kelity, Edina;Sommitsch, Christof",
title = "Prediction and validation of hot tearing in permanent mold steel casting using a viscoplastic damage model",
journal = "Computer Methods in Materials Science",
volume = "13",
address = "Institute for Materials Science and Welding, Graz, AUT",
pages = "36-42",
year = "2013",
url = "www.cmms.agh.edu.pl/abstract.php?p_id=408"}