• Title/Summary/Keyword: Laser overlap welding

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Prevention of Back Side Humping in Laser Welding of Al 5J32 Alloy by Using Laser Power Modulation (Al 5J32 합금의 레이저 용접에서 레이저출력 모듈레이션을 이용한 이면 험핑 비드의 안정화)

  • Ahn, Do-Chang;Kim, Cheol-Hee;Kim, Jae-Do
    • Journal of Welding and Joining
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    • v.29 no.4
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    • pp.80-84
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    • 2011
  • In the 5xxx series Al-Mg alloy, magnesium addition can increase the strength of aluminum alloy by solid solution strengthening but it has a relatively low melting and boiling temperature. During full -penetration laser welding of the Al-Mg alloys, its low boiling point and high vapor pressure brings about the spiky humping bead on the bottom side. Under back-side shielding, the spiking of back bead can be reduced but it restraints the process flexibility. In this study, a square pulse waveform modulation was employed to stabilize keyhole and back bead surface without back-side shielding. By using an experimental design, the bead shapes were evaluated for various process parameters such as the focal position, welding velocity and waveform parameters and the smooth back bead shape could be achieved.

Applicability Study of 2-pass Laser Welding on Galvanized Steel Sheets (아연도금강판 겹치기 용접부에 대한 2패스 레이저용접 적용성 연구)

  • Ahn, Young-Nam;Kang, Minjung;Kim, Cheolhee
    • Journal of Welding and Joining
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    • v.34 no.4
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    • pp.55-61
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    • 2016
  • During laser overlap welding of galvanized steel sheets, explosion of weld pool by the high pressure zinc vapor induces weld defects like porosity and blowhole. In this study, laser 2-pass welding was implemented to prevent the weld defects. Through the 1st pass welding, zinc layers on the faying surfaces were removed when proper heat input was applied. Excessive heat input could result in explosion even during the 1st pass welding and insufficient heat input could not remove enough region of zinc layer for the 2nd pass welding. Coating weights of $45g/m^2$ and $60g/m^2$ were considered and for both cases sound welds without weld defects could be achieved. In spite of 2-pass welding, softening of weld and heat affected zone was not observed and Zn coating was not diluted into the weld metal.