Abstract
Counter-gravity filling and pressurization during solidification have been separately shown to improve casting quality in sand cast steel. Studies and industry practice show that counter-gravity filling increases the yield and reduces reoxidation inclusions. Other studies show pressurization during solidification has the potential to increase the feeding effectivity of risers, which leads to a reduction in centerline shrinkage. In the present study, a method for sand casting steel is developed that combines both practices. Casting simulations are used to determine key events during the process. Counter-gravity filling of a sand mold with liquid steel is performed by linearly decreasing pressure to a value of 0.053 MPa and holding this pressure for 40 s. After the vacuum pressure is released, the entire system is pressurized to a maximum pressure of 0.35 MPa, 220 s after the start of the filling process. The casting method is applied to cylindrical bar castings. Radiographic and dye penetrant inspection of the bars shows no detectable centerline porosity forms when the casting system is pressurized, unlike the gravity-poured control castings.
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Acknowledgments
This material is based upon work supported by the Department of Energy under Award Number DE-EE006428. The authors would like to thank Jerry Thiel, Sairam Ravi and the staff and students at the University of Northern Iowa for their help in performing the casting experiments.
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Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.
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Archer, L., Hardin, R.A. & Beckermann, C. Counter-Gravity Sand Casting of Steel with Pressurization During Solidification. Inter Metalcast 12, 596–606 (2018). https://doi.org/10.1007/s40962-017-0200-5
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DOI: https://doi.org/10.1007/s40962-017-0200-5