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Project Fact Sheet 
PREVENTION OF POROSITY IN IRON CASTINGS 
BENEFITS 
The results of this project will help metal 
casters to understand, predict and prevent 
porosity formation in iron castings. As a 
result, scrap will be significantly reduced. 
Researchers estimate that the results of this 
project could reduce scrap, and therefore 
melting requirements, by as much as seven 
percent. 
APPLICATIONS 
The results of this project can be applied in 
casting design and foundry operations 
throughout the iron castings industry. In 
addition to improving cost competitiveness 
and energy efficiency by predicting and 
mitigating porosity formation, damages 
caused by unexpected failure of castings will 
be reduced. 
MODEL WILL TEACH MECHANISMS OF POROSITY FORMATION AND 
ENABLE FOUNDRIES TO IMPLEMENT PREVENTIVE MEASURES 
For most foundries, porosity problems occur sporadically, but even occasional 
outbreaks can be costly. Even a small amount of porosity can significantly reduce 
the mechanical properties of the castings; as a result, the casting will have to be 
scrapped. In general, ½ to ¾ of the all-scrap castings are lost to factors related, 
directly or indirectly, to porosity. Despite the obvious importance of the problem, 
there is no consensus on how to deal with it. 
Most porosity in iron castings is believed to be a result of the combination of 
solidification shrinkage and a decrease in the solubility of gases during 
solidification. Unfortunately, there are insufficient data to support this theory. 
Therefore, it is essential for the foundries to learn the mechanisms of porosity 
formation and other effects of gases in their iron castings. It is also essential to 
establish a quantitative relationship among the factors affecting porosity 
formation, in a form that can be used to predict its formation in a production 
environment. 
In this project, researchers from Climax Research Services and Albany Research 
Center will develop a model to help foundries learn the mechanisms of porosity 
formation and other effects of gases. They will also establish the quantitative 
relationship among factors affecting porosity formation. The model will be 
commercialized for use throughout the metal casting industry. 
PREVENTING POROSITY IN IRON CASTINGS 
Interdendritic porosity in a Ni-Hard I casting melted and solidified under 1 atm 
nitrogen pressure. 
OFFICE OF INDUSTRIAL TECHNOLOGIES 
ENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY
Project Description 
Goal: The goal of this project is to develop a model to help foundries learn the 
mechanisms of porosity formation and other effects of gases in their iron castings. 
It will establish a quantitative relationship among the factors affecting porosity 
formation and better enable foundry operator to reduce/eliminate porosity 
formation in a production environment. 
Progress and Milestones 
In castings, porosity formation is generally the result of an excessive gas content of the 
liquid alloy, or solidification shrinkage, or a combination of both. 
A number of studies have been done to understand the mechanism of gas and 
shrinkage porosity formation and to develop models to predict porosity formation. Most 
of the research conducted on porosity formation have attacked only a few sides of the 
problem rather than dealing with the whole picture. There is a need to generate data 
covering all of the variables affecting porosity formation, using the same alloy, in order 
to understand the problem as a whole. 
In this project, the modeling work is focusing on the unbalancing of several pressure 
terms, such as pressure exerted by solidification shrinkage, the increasing gas 
concentration in the remaining liquid due to reduced solubility in the solid, the surface 
tension between gas and liquid, the metallostatic head on the casting, and the ambient. 
Each of these pressure terms can be evaluated, and conditions which favor pore 
formation can be determined experimentally. Thus, a model incorporating all the 
variables will be developed. 
This three year project was awarded in August 2000. The project was formed with input 
from the American Foundry Society (AFS) member foundries, with the most valuable 
contribution being their input in the future direction of research. 
PROJECT PARTNERS 
Climax Research Services 
Wixom, MI 
Albany Research Center 
Albany, OR 
Borden Chemicals, Toledo, OH 
Citation, Birmingham, AL 
Columbia Steel Castings, Portland, OR 
Durametal, Muncy, PA 
Georgia Iron Works, Grovetown, GA 
Intermet, Lynchburg, VA 
Maca Supply, Springville, UT 
Texaloy Foundry, Floresville, TX 
United Foundries, Canton, OH 
United Machine & Foundry, Winona, MN 
FOR ADDITIONAL INFORMATION, 
PLEASE CONTACT: 
Harvey Wong 
Office of Industrial Technologies 
Phone: (202) 586-9235 
Fax: (202) 586-6507 
Harvey.Wong@ee.doe.gov 
http://www.oit.doe.gov/IOF/metalcast/ 
Please send any comments, 
questions, or suggestions to 
webmaster.oit@ee.doe.gov. 
Visit our home page at 
www.oit.doe.gov 
Office of Industrial Technologies 
Energy Efficiency 
and Renewable Energy 
U.S. Department of Energy 
Washington, D.C. 20585 
January 2001