R. Hardin, and C. Beckermann

(sponsored through the Cast Metal Coalition, CMC, by DOE and numerous steel foundries within the Steel Founders' Society of America, SFSA)
Project Fact Sheet from DOE

The Steel Founders Society of America (SFSA) home page can be found here: SFSA

Heat treatment and associated processing, such as quenching, are critical during high strength steel casting production. These processes must be managed closely to prevent thermal and residual stresses that may result in distortion, cracking (particularly after machining), rework, and weld repair. The risk of casting distortion limits aggressive quenching that can be beneficial to the process and yield an improved outcome. As a result of these distortions, adjustments must be made to the casting or pattern design or tie bars added. Straightening castings after heat treatments can be both time-consuming and expensive. Residual stresses may reduce a casting’s overall service performance, possibly resulting in catastrophic failure. Stress relieving may help, but expends additional energy in the process. Casting software is very limited in predicting distortions during heat treatment, so corrective measures most often involve a tedious trial and error procedure.

According to researchers from the University of Iowa, the casting process must be considered when attempting to predict the final dimensions and residual stresses that may develop after heat treatment. These researchers have investigated the stresses and distortions that develop during solidification and cooling, before the heat treatment stage begins. Extending modeling capabilities to the heat treatment processes, the researchers will examine microstructural and property changes in the steel, in addition to heat transfer and stresses that develop during the heating and quenching processes. The proposed project will develop and verify a model for predicting the distortions and residual stresses that occur during heat treatment of steel castings.

The goal of this project is to develop a model for predicting the distortions and residual stresses that develop during heat treatment of steel castings. Foundry engineers will then be able to reduce trial and error processing, and economically use heat treatment resources.

The objectives of this research are:

• develop and implement a model into an existing casting simulation code to predict distortion and residual stress development during heat treatment of steel castings,
• perform a casting/heat treatment experiment to test and validate the model,
• apply the simulation model to a production casting in a case study illustrating the use of the model in foundry practice.