Basic Study on Remelting Process to Enhance Density of Inconel 625 in Direct Energy Deposition
Ryo Koike*,†, Taro Misawa*, Yasuhiro Kakinuma*, and Yohei Oda**
*Department of System Design Engineering, Keio University
3-14-1 Hiyoshi, Kouhoku-ku, Yokohama 223-8521, Japan
**DMG Mori Seiki Co., Ltd., Nagoya, Japan
Although the applicability of additive manufacturing (AM) to the production of complex shapes has attracted attention from the automobile and aerospace industries, companies hesitate to introduce AM processes because of their low reliability, which is due to pores inside the produced parts. Consequently, many researchers have experimentally evaluated the relation between the pore evolution and production conditions in AM processes. On the other hand, several studies have focused on finishing processes in order to enhance the quality of AM production, considering that production quality cannot be improved enough only by modifying the production conditions in AM processes. To reduce pores in a metal product, hot isostatic pressing (HIP), which applies high pressure and heat energy to metal AM products and enhances production density, has proven to be an efficient approach. However, special equipment is required to produce a high-temperature and high-pressure environment, leading to high cost and low productivity. From the view point of practicability, a simple finishing process would be a fundamental solution to make metal AM processes highly reliable. This paper therefore proposes a method of reducing pores through a remelting process in the direct energy deposition of Inconel 625. Furthermore, a method of doing a graphical analysis to evaluate the bias of pore distribution in the deposited object is proposed. The pore reduction effect in remelting is experimentally evaluated by irradiating the low density area with a laser beam, and a graphical evaluation clarifies that the concentration of residual pores occurs in the top layer of a deposited object. As a result, residual pores are eliminated with certainty through the remelting process. The density of the deposit can be enhanced easily and without any complicated finishing systems with just the laser system originally introduced in a DED machine.
-  G. Levy, R. Schidel, and J. Kruth, “Rapid Manufacturing and Rapid Tooling with Layer Manufacturing (LM) Technologies, State of the Art and Future Perspectives,” CIRP Ann., Vol.52, No.2, pp. 589-609, 2003.
-  I. Gibson, D. W. Rosen, and B. Stucker, “Additive Manufacturing Technologies,” Springer, p. 238, 2010.
-  T. Abe and H. Sasahara, “Dissimilar Metal Deposition with a Stainless Steel and Nickel-based Alloy Using Wire and Arc-based Additive Manufacturing,” Precis. Eng., Vol.45, pp. 387-395, 2016.
-  Q. Wang, S. Zhang, C. Zhang, C. Wu, J. Wang, J. Chen, and Z. Sun, “Microstructure Evolution and EBSD Analysis of a Graded Steel Fabricated by Laser Additive Manufacturing,” Vacuum, Vol.141, pp. 68-81, 2017.
-  M. Javidani, J. A. Zavala, J. Danovitch, Y. Tian, and M. Brochu, “Additive Manufacturing of AlSi10Mg Alloy Using Direct Energy Deposition Microstructure and Hardness Characterization,” J. Therm. Spray Tech., Vol.26, pp. 587-597, 2017.
-  J. S. Keist and T. A. Palmer, “Development of Strength-Hardness Relationships in Additively Manufactured Titanium Alloys,” Mater. Sci. & Eng. A, Vol.693, pp. 214-224, 2017.
-  Y. Kakinuma, M. Mori, Y. Oda, T. Mori, M. Kashihara, A. Hansel, and M. Fujishima, “Influence of Metal Powder Characteristics on Product Quality with Directed Energy Deposition of Inconel 625,” CIRP Ann., Vol.65, No.1, pp. 209-212, 2016.
-  C. Zhong, A. Gasser, T. Schopphoven, and R. Poprawe, “Experimental Study of Porosity Reduction in High Deposition-rate Laser Material Deposition,” Opt. Laser Technol., Vol.75, pp. 87-92, 2015.
-  L. Wang, P. Pratt, S. D. Felicelli, H. E. Kadin, J. T. Berry, P. T. Wang, and M. F. Horstemeyer, “Experimental Analysis of Porosity Formation in Laser-Assisted Powder Deposition Process,” J. of the Minerals, Metals & Materials Society, Vol.1, pp. 389-396, 2009.
-  W. W. Wits, S. Carmignato, F. Zanini, and T. H. J. Vaneker, “Porosity Testing Methods for the Quality Assessment of Selective Laser Melted Parts,” CIRP Ann, Vol.65, No.1, pp. 201-204, 2016.
-  A. Kreitcberg, V. Brailovski, and S. Turenne, “Effect of Heat Treatment and Hot Isostatic Pressing on the Microstructure and Mechanical Properties of Inconel 625 Alloy Processed by Laser Powder Bed Fusion,” Mater. Sci. & Eng. A, Vol.689, pp. 1-10, 2017.
-  J. J. Lewandowski and M. Seifi, “Metal Additive Manufacturing: A Review of Mechanical Properties,” Annual Review of Materials Research, Vol.46, pp. 151-186, 2016.
-  C. Zhong, A. Gasser, J. Kittel, K. Wissenbach, and R. Poprawe, “Improvement of Material Performance of Inconel 718 Formed by High Deposition-rate Laser Metal Deposition,” Material & Design, Vol.98, pp. 128-134, 2016.
-  P. J. Withers, I. Todd, and P. B. Prangnell, “The Effectiveness of Hot Isostatic Pressing for Closing Porosity in Titanium Parts Manufactured by Selective Electron Beam Melting,” Metallurgical and Materitals Trans. A, Vol.47, No.5, pp. 1939-1946, 2016.
-  S. C. Lee, S. H. Chang, T. P. Tang, H. H. Ho, and J. K. Chen, “Improvement in Microstructure and Tensile Properties of Inconel 718 Superalloy by HIP Treatment,” Materials Trans., Vol.47, No.11, pp. 2877-2881, 2006.
-  J. Potgieter, O. Diegel, F. Noble, and M. Pike, “Additive Manufacturing in the Context of Hybrid Flexible Manufacturing Systems,” Int. J. of Automation Technol., Vol.6, No.5, pp. 627-632, 2012.
-  ASTM International, “Standard Terminology for Additive Manufacturing Technologies,” F2792-12a, 2013.
-  T. Kuriya, R. Koike, Y. Kakinuma, and T. Mori, “Relationship between solidification time and porosity with directed energy deposition of Inconel 718,” Proc. of The 9th Int. Conf. on Leading Edge Manufacturing in 21st Century, 2017.
-  A. Raghavan, L. Wei, T. A. Palmer, and T. DebRoy, “Heat Transferr and Fluid Flow in Additive Manufacturing,” J. of Laser Applications, Vol.25, No.5, 052006, 2013.
-  R. Rai, G. G. Roy, and T. DebRoy, “A Computationally Effcient Model of Convective Het Transfer and Solidification Characteristics during Keyhole Mode Laser Welding,” J. Appl. Phys., No.101, 054909, 2007.
-  J. C. Heigel, P. Michaleris, and T. A. Palmer, “Measurement of Forced Surface Convection in Directed Energy Deposition Additive Manufacturing,” Proc. IMechE Part B, J. Engineering Manufacture, Vol.230, No.7, pp. 1295-1308, 2016.
This article is published under a Creative Commons Attribution-NoDerivatives 4.0 Internationa License.