Abstract
A comprehensive methodology that takes into account solidification, shrinkage-driven interdendritic fluid flow, hydrogen precipitation, and porosity evolution has been developed for the prediction of the microporosity fraction and distribution in aluminum alloy castings. The approach may be used to determine the extent of gas and shrinkage porosity, i.e., the resultant microporosity which occurs due to gas precipitation and that which occurs when solidification shrinkage cannot be compensated for by the interdendritic fluid flow. A solution algorithm in which the local pressure and microporosity are coupled is presented, and details of the implementation methodology are provided. The models are implemented in a computational framework consistent with that of commonly used algorithms for fluid dynamics, allowing a straightforward incorporation into existing commercial software. The results show that the effect of microporosity on the interdendritic fluid flow cannot be neglected. The predictions of porosity profiles are validated by comparison with independent experimental measurements by other researchers on aluminum A356 alloy test castings designed to capture a variety of solidification conditions. The numerical results reproduce the characteristic microporosity profiles observed in the experimental results and also agree quantitatively with the experimentally measured porosity levels. The approach provides an enhanced capability for the design of structural castings.
| Original language | English |
|---|---|
| Pages (from-to) | 243-255 |
| Number of pages | 13 |
| Journal | Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science |
| Volume | 33 |
| Issue number | 2 |
| DOIs | |
| State | Published - Apr 2002 |
Funding
This work was performed under a Cooperative Research and Development Agreement (CRADA) with the United States Advanced Materials Partnership (USAMP), United States Council for Automotive Research (USCAR) for the project on Design and Product Optimization for Cast Light Metals. This research was sponsored by the United States Department of Energy, Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Transportation Technologies, Lightweight Vehicle Materials Program and Office of Heavy Vehicle Technologies, under Contract No. DE-AC05-96OR22464 with Lockheed Martin Energy Research Corp. and DE-AC05-00OR22725 with UT– Battelle, LLC. This research was supported, in part, by appointments to the Oak Ridge National Laboratory Postdoctoral Research Associates Program, administered jointly by the Oak Ridge Institute for Science and Education and Oak Ridge National Laboratory. The authors also thank D.B. Kothe (Los Alamos National Laboratory), for providing access to the Telluride code for the computations done in this study; Q. Han and S.R. Agnew for reviewing the paper; and M.L. Atchley for preparing the manuscript.
| Funders | Funder number |
|---|---|
| Office of Heavy Vehicle Technologies | DE-AC05-00OR22725, DE-AC05-96OR22464 |
| Office of Transportation Technologies | |
| U.S. Department of Energy | |
| Battelle | |
| Office of Energy Efficiency and Renewable Energy | |
| Oak Ridge National Laboratory | |
| Oak Ridge Institute for Science and Education |