This study theoretically investigates the effects of the entrainment accompanying mass, momentum, and energy transport on pore size during high power density laser and electron beam welding processes. The physics of macroporosity formation is not well understood, even though macroporosity often occurs and limits the widespread industrial application of keyhole mode welding. This work is an extension of a previous work dealing with collapses of keyholes induced by high intensity beam drilling. In order to determine the pore shape, this study, however, introduces the equations of state at the times when the keyhole is about to be enclosed and when the temperature drops to melting temperature. The gas pressure required at the time when keyhole collapses is determined by calculating the compressible flow of the two-phase, vapor–liquid dispersion in a vertical keyhole with varying cross sections, paying particular attention to the transition between annular and slug flows. It is found that the pore size increases as entrainment fluxes decrease in the lower and upper regions of the keyhole containing a supersonic mixture. The pore size also increases with decreasing total energy of entrainment and an increasing axial velocity component ratio between entrainment and mixture through the core region. With a subsonic mixture in the keyhole, the final pore size increases with entrainment fluxes in the lower and upper regions. This work provides an exploratory and systematical investigation of pore size induced by entrainment accompanied by mass, momentum, and energy transport during keyhole mode welding.
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The Effects of Entrainment on Pore Shape in Keyhole Mode Welding
P. S. Wei,
P. S. Wei
1
Professor
Department of Mechanical
and Electro-Mechanical Engineering,
e-mail: pswei@mail.nsysu.edu.tw
Department of Mechanical
and Electro-Mechanical Engineering,
National Sun Yat-Sen University
,Kaohsiung 80424
, Taiwan, ROC
e-mail: pswei@mail.nsysu.edu.tw
1Corresponding author.
Search for other works by this author on:
T. C. Chao
T. C. Chao
Department of Mechanical
and Electro-Mechanical Engineering,
e-mail: m993020071@student.nsysu.edu.tw
and Electro-Mechanical Engineering,
National Sun Yat-Sen University
,Kaohsiung 80424
, Taiwan, ROC
e-mail: m993020071@student.nsysu.edu.tw
Search for other works by this author on:
P. S. Wei
Professor
Department of Mechanical
and Electro-Mechanical Engineering,
e-mail: pswei@mail.nsysu.edu.tw
Department of Mechanical
and Electro-Mechanical Engineering,
National Sun Yat-Sen University
,Kaohsiung 80424
, Taiwan, ROC
e-mail: pswei@mail.nsysu.edu.tw
T. C. Chao
Department of Mechanical
and Electro-Mechanical Engineering,
e-mail: m993020071@student.nsysu.edu.tw
and Electro-Mechanical Engineering,
National Sun Yat-Sen University
,Kaohsiung 80424
, Taiwan, ROC
e-mail: m993020071@student.nsysu.edu.tw
1Corresponding author.
Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received July 23, 2014; final manuscript received November 5, 2014; published online April 16, 2015. Assoc. Editor: Zhixiong Guo.
J. Heat Transfer. Aug 2015, 137(8): 082102 (9 pages)
Published Online: August 1, 2015
Article history
Received:
July 23, 2014
Revision Received:
November 5, 2014
Online:
April 16, 2015
Citation
Wei, P. S., and Chao, T. C. (August 1, 2015). "The Effects of Entrainment on Pore Shape in Keyhole Mode Welding." ASME. J. Heat Transfer. August 2015; 137(8): 082102. https://doi.org/10.1115/1.4029039
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