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Research Papers

The Effects of Drilling Parameters on Pore Size in Keyhole Mode Welding

[+] Author and Article Information
P. S. Wei

Fellow and Professor
Department of Mechanical
and Electro-Mechanical Engineering,
National Sun Yat-Sen University,
Kaohsiung 80424, Taiwan
e-mail: pswei@mail.nsysu.edu.tw

T. C. Chao

Graduate Student
Department of Mechanical
and Electro-Mechanical Engineering,
National Sun Yat-Sen University,
Kaohsiung 80424, Taiwan
e-mail: m993020071@student.nsysu.edu.tw

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received December 31, 2014; final manuscript received April 21, 2015; published online September 9, 2015. Assoc. Editor: Wayne Cai.

J. Manuf. Sci. Eng 138(2), 021008 (Sep 09, 2015) (10 pages) Paper No: MANU-14-1722; doi: 10.1115/1.4030531 History: Received December 31, 2014

The pore sizes affected by different drilling parameters during high power density laser and electron beam welding processes are theoretically determined in this study. The drilling parameters include incident energy absorbed by the mixture in the keyhole, radius, and Mach number at the base, drilling speed, and location of the shock wave or surrounding pressure. The factors affecting the pore sizes are still lacking, even though porosity often occurs and limits the widespread industrial application of keyhole mode welding. In order to determine the pore shape, this study 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, temperature, and volume required at the time when the keyhole is about to be closed are determined by calculating the compressible flow of the 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 final pore size decreases as absorbed energy, radius, and Mach number at the base increase, and decreases axial location of the shock wave or higher surrounding pressure for the keyhole containing a supersonic mixture. For a subsonic mixture in the keyhole, the final pore size decreases as released energy, radius, and Mach number at the base increase. This work provides an exploratory and systematical investigation of the pore size during keyhole mode welding.

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Figures

Grahic Jump Location
Fig. 1

(a) The physical model and coordinate system and (b) pore formation from the enclosure of the keyhole

Grahic Jump Location
Fig. 2

Comparison of axial variations in dimensionless mixture temperature, pressure, Mach number, and keyhole radius for (a) different grid systems and between (b) exact closed-form and numerical results for a supersonic flow

Grahic Jump Location
Fig. 3

The effects of dimensionless energy absorbed by mixture on (a) dimensionless final pore size, maximum length, radius, and volume and (b) dimensionless average temperature and pressure at the time when the keyhole containing a supersonic mixture is about to be closed

Grahic Jump Location
Fig. 4

Porosity occurs in the welding of Al 5083 [62]

Grahic Jump Location
Fig. 5

The effects of dimensionless energy released by mixture on (a) dimensionless final pore size, maximum length, radius, and volume and (b) dimensionless average temperature and pressure at the time when the keyhole containing a subsonic mixture is about to be closed

Grahic Jump Location
Fig. 6

The effects of dimensionless keyhole base radius on (a) dimensionless final pore size, maximum length, radius, and volume and (b) dimensionless average temperature and pressure at the time when the keyhole containing a supersonic mixture is about to be closed

Grahic Jump Location
Fig. 7

The effects of dimensionless keyhole base radius on (a) dimensionless final pore size, maximum length, radius, and volume and (b) dimensionless average temperature and pressure at the time when the keyhole containing a subsonic mixture is about to be closed

Grahic Jump Location
Fig. 8

The effects of Mach number at the base on (a) dimensionless final pore size, maximum length, radius, and volume and (b) dimensionless average temperature and pressure at the time when the keyhole containing a supersonic mixture is about to be closed

Grahic Jump Location
Fig. 9

The effects of Mach number at the base on (a) dimensionless final pore size, maximum length, radius, and volume and (b) dimensionless average temperature and pressure at the time when the keyhole containing a subsonic mixture is about to be closed

Grahic Jump Location
Fig. 10

The effects of dimensionless drilling speed on (a) dimensionless final pore size, maximum length, radius, and volume and (b) dimensionless average temperature and pressure at the time when the keyhole containing a subsonic mixture is about to be closed

Grahic Jump Location
Fig. 11

The effects of dimensionless location of shock wave on (a) dimensionless final pore size, maximum length, radius, and volume and (b) dimensionless average temperature and pressure at the time when the keyhole containing a supersonic mixture is about to be closed

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