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Research Papers

Welding of Alumina Using a Pulsed Dual-Beam CO2 Laser

[+] Author and Article Information
J. Harris, R. Akarapu

Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802

A. E. Segall

Engineering Science and Mechanics, Pennsylvania State University, University Park, PA 16802aesegall@psu.edu

J. Manuf. Sci. Eng 133(1), 011001 (Jan 05, 2011) (6 pages) doi:10.1115/1.4003119 History: Received April 17, 2009; Revised November 12, 2010; Published January 05, 2011; Online January 05, 2011

Despite the many advantages of using lasers for welding ceramics (alumina in particular), cracks induced by the resulting and severe thermal stresses are often detrimental to weld quality and strength. While many factors contribute to the formation of these cracks, it is the inevitable and localized increase in temperature and the ensuing thermal stresses that usually cause the damage. To help avoid the use of a separate preheating step, while at the same time allowing for faster joining, a unique method of dual-beam laser welding was developed and qualitatively assessed. The approach outlined in this paper utilizes two beams split from a single, 500 W (1.5 kW peak) CO2 system to more gradually introduce the energy required to melt and bond alumina. The first or lead beam raises the local temperature just below the melting point, while the second beam introduces additional heat sufficient to melt and bond the samples. Using feed rates of 5.1 mm/s and beam separation distances ranging from 0.5 mm to 2.3 mm, clean and relatively straight weld geometries were observed at total power levels of approximately 250W+. Relatively straight and uniform welds with considerable dross occurred at smaller beam separations and higher power levels. Uneven weld lines sans discernible cracks were observed at power levels below 206 W. Based on these preliminary observations, the two-beam approach was qualitatively shown to be capable of influencing and, in some instances, improving weld characteristics in terms of overall quality, dross, and crack formation.

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Copyright © 2011 by American Society of Mechanical Engineers
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Figures

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Figure 1

Customized dual-beam system with independent power control

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Figure 2

Welding fixture used for the dual-beam welding experiments

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Figure 3

Welding configuration and geometry

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Figure 4

Typical crack geometry seen after single-beam welding (feed rate of 7.62 mm/s, power of 425 W, and a duty cycle of 30%)

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Figure 5

Typical severe cracks observed after single-beam welding including (a) a crack parallel to weld, (b) cracks in weld, (c) a crack that crosses into the weld, and (d) a crack due to edge effects; all samples had a feed rate of 8.89 mm/s, power of 370 W, and a duty cycle of 25%

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Figure 6

Weld geometries observed after dual-beam welding: ((a) and (b)) front and back, respectively, of weld with good geometry (beam separation=0.316 mm, duty cycle=8%), (c) front of weld with splatter (beam separation=0.158 mm, duty cycle was 14%), (d) back of weld with splatter (beam separation=2.2 8 mm, duty cycle=13%), ((e) and (f)) front and back, respectively, of weld with poor geometry (beam separation=0.485 mm, duty cycle=12%)

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