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Metal Casting Technologies : Whos who September 2011
60 www.metals.rala.com.au TECHNICAL FEATURE References  M. Asta, C. Beckermann, A. Karma, W. Kurz, R. Napolitano, M. Plapp, G. Purdy, M. Rappaz and R. Trivedi, "Solidification microstructures and solid-state parallels: Recent developments, future directions." Journal of Acta Materialia, Vol. 57, 2009, 941--971.  M. Avalle, G. Belingardi, M. Cavatorta and R. Doglione, "Casting defects and fatigue strength of a die cast aluminum alloy: a comparison between standard specimens and production components." International Journal of Fatigue, Vol. 24, 2002, 1--9.  D. Gunasegaram, D. Farnsworth and T. Nguyen. "Identification of critical factors affecting shrinkage porosity in permanent mold casting using numerical simulations based on design of experiments." Journal of Materials Processing Technology, Vol. 209, 2009, 1209--1219.  H. Mayer, M. Papakyriacou, B. Zettl and S. Stanzl-Tschegg, "Influence of porosity on the fatigue limit of die cast magnesium and aluminium alloys." International Journal of Fatigue, Vol. 25, 2003, 245--256.  T. Vijayaram, S. Sulaiman, A. Hamouda and M. Ahmad, "Numerical simulation of casting solidification in permanent metallic molds." Journal of Materials Processing Technology, Vol. 178, 2006, 29--33.  A. Reisa, Y. Houbaertc, Z. Xub, R. Van Tol, A. Santosa, J. Duartea and A. Magalha, "Modeling of shrinkage defects during solidification of long and short freezing materials." Journal of Materials Processing Technology, Vol. 202, 2008, 428--434.  P. Cleary, J. Ha, M. Prakash and T. Nguyen, "Short shots and industrial case studies: Understanding fluid flow and solidification in high pressure die casting." Applied Mathematical Modelling, Vol. 34, 2010, 2018--2033.  X. Zhang, S. Xiong and Q. Xu, "Numerical methods to improve the computational efficiency of solidification simulation for the investment casting process." Journal of Materials Processing Technology, Vol. 173, 2006, 70--74.  C. Kang, Y. Son and S. Youn, "Experimental investigation of semi-solid casting and die design by thermal fluid solidification analysis." Journal of Materials Processing Technology, Vol. 113, 2001, 251-256.  D. O'Mahoney and D. Browne, "Use of experiment and an inverse method to study interface heat transfer during solidification in the investment casting process." Experimental Thermal and Fluid Science, Vol. 22, 2000, 111-122.  G. Upadhya, S. Das, U. Chandra and A. Paul, "Modelling the investment casting process: a novel approach for view factor calculations and defect prediction." Applied Mathematical Modelling, Vol. 19, 1995, 354-362.  A. Dahle and D. StJohn, "Rheological behaviour of the mushy zone and its effect on the formation of casting defects during solidification." Acta Material, Vol. 47, No. 1, 1999, 31-41.  L. Zhang, H. Shen, Y. Ronga and T. Huang, "Numerical simulation on solidification and thermal stress of continuous casting billet in mold based on meshless methods." Materials Science and Engineering A, Vol. 466, 2007, 71--78.  I. Kazantseva, I. Lemahieub, G. Salova and R. Denysc, "Statistical detection of defects in radiographic images in nondestructive testing." Signal Processing, Vol. 82, 2002, 791 -- 801.  D. Shi, T. Gang, S. Yang and Y. Yuan, "Research on segmentation and distribution features of small defects in precision weldments with complex structure." NDT & E International, Vol. 40, 2007, 397--404.  R. da Silva, L. Caloba, M. Siqueira and J. Rebello, "Pattern recognition of weld defects detected by radiographic test." NDT & E International, Vol. 37, 2004, 461--470.  I. Yang, K. Im, D. Hsu, V. Dayal, D. Barnard, J. Kim, C. Cha, Y. Cho and D. Kim, "Feasibility on fiber orientation detection of unidirectional CFRP composite laminates using one-sided pitch--catch ultrasonic technique." Composites Science and Technology, Vol. 69, 2009, 2042--2047.  C. Jen, J. Moisan, C. Zheng, C. Loong, S. Kruger, M. Shehata and E. Essadiqi, "In-line ultrasonic monitoring of semi-solid magnesium die casting process." Ultrasonics, Vol. 41, 2004, 777--784.  S. Deutsch, "Preliminary study of the fluid mechanics of liquid penetrant testing." Journal of Research of the National Bureau of Standards, Vol. 84, No. 4, 1979, 287-291. Dr Wisam M. Abu-Jadayil is an assistant Professor of Industrial and Mechanical Engineering in the Department of Industrial Engineering at the Hashemite University in Jordan. His interests are in design and manufacturing materials and processes automation, using NC/CNC and DNC machines, geometric modeling, computer graphics, visualization, simulation, optimization, virtual reality, human-computer interaction and statistical analysis. These results are expected, that solidification and transformation to the solid state starts from the surfaces and the last portion that solidifies is the sample core. When the sample is taken out from the casting mold after sufficient time for solidification, then all or most of the sample is transformed to the solid state and very little internal defects may form. But when the sample is removed from the casting mold before the sample core is solidified, then that portion is forced to solidify very fast outside the casting mold, which creates internal defects in the casting sample that the internal portion of the sample has very limited chance to expand or shrink while the external portion is already solidified. The results of this UT agree with what was found by Reis et. al. . They reported that short freezing of casting samples results in more internal defects, and this is exactly what happened in this research. Conclusion The Al sand casting defects was studied in this research using two nondestructive testing techniques; the penetrant testing (PT) and the ultrasonic testing (UT). The following conclusions can be drawn from this study: ● For casting of Al using nonpermanent sand mold, as the solidification time is increasing, that the sample left longer inside the casting mold, as the number of surface defects is getting less, with better surface finish of the casting sample. ● When the internal defects of the Al casting sample were inspected, same influence of the solidification time was found; as the solidification time is increasing, the internal defects are decreasing and getting closer to the surface. ● The PT is a good nondestructive technique that can be used successfully for inspecting casting surface defects easily. PT results are descriptive and not so accurate, but give a clear indication of the general trend. ● The UT is a good nondestructive technique that can be used for inspecting internal casting defects with good accuracy. Results of UT are acceptable but they are limited to the tested location of the sample. ■
Whos who September 2012