• Proceedings of the KWS Conference
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• 2007.11a
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• pp.354-356
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• 2007

• Proceedings of the KWS Conference
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• 2005.06a
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• pp.100-102
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• 2005

• Journal of Welding and Joining
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• v.7 no.4
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• pp.12-21
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• 1989

Laser beam welding parameters have experimentally investigated, using a continuous wave 3kW $CO_2$ laser with the various travel speeds, beam mode and laser beam power in low carbon steels. An optimum position of focus and the effect of shielding gas on penetration depth with varying the flow range of 0.5 to 5.1m/min have been combined to investigate the effect of laser power and travel speed on penetration depth and bead width. It is found that the optimum position of focus in 3kW class laser is 0.5 to 1.5mm below the surface of the material. The flow rate of shielding gas affects the penetration depth and He is more effective than Ar. The penetration depth in laser welds of low carbon steels is between two and four times of the bead width. Laser beam welding of butt joints in 2mm thick carbon steel has been carried out to establish a weldability lobe. The lobe indicating acceptable welding conditions is introduced.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.33 no.11
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• pp.1256-1261
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• 2009

Today, implementation of the defect detection in laser welding has been researched for a long time, but most studies have been made around thin plate within $1{\sim}3mm^t$. Therefore, this study was measured and analyzed light emission signals of the induced plasma in $CO_2$ laser lap welding of $6mm^t$ Zn primer-coated steel, and based on this analysis, research made an investigation into possibility of monitoring in thick plate welding. It was been analyzing the measured signals by RMS and FFT processing, as a results, we were able to confirm definite difference of two signals between humping bead and sound bead. Thus, possibility of real time monitoring in $CO_2$ laser lap welding verified experimentally.

• Proceedings of the Korean Society of Laser Processing Conference
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• 1999.05a
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• pp.24-26
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• 1999

• Proceedings of the KWS Conference
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• 1999.10a
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• pp.218-219
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• 1999

• Proceedings of the KWS Conference
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• 1999.05a
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• pp.13-16
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• 1999

• Journal of Advanced Marine Engineering and Technology
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• v.28 no.1
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• pp.109-115
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• 2004

The spatter and porosity could be occurred during$CO_2$CW laser welding of Primer- coated steel for shipbuilding. This study has suggested an alternative idea by examining of weld-defect formation mechanism. The primer-coated plate induced the spatter humping bead and porosity and these are main part of the welding defect. attributed to the powerful vaporizing pressure of primer attached on the base metal The zinc of Primer has a boiling point that is the lower temperature than melting point of steel zinc vapor will build up at the interface between the two sheets and this tends to deteriorate the quality of the weld by ejecting weld material from lap position or leaving porosity. Therefore introducing a small gap clearance in the lap position. the zinc vapor could escape through it and sound weld beads can be acquired. In conclusion, we suggested the occurred and prevented mechanism of weld defects with searching the factor.

• Laser Solutions
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• v.5 no.1
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• pp.13-21
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• 2002

Compared to conventional welding process, laser welding does not use additional filler wire generally. However, if laser welding uses the filler wire, the applicability of the method can be broaden. When laser welding uses the filler wire, it is possible to enhance gap bridging ability and to prevent cracking in weld pool by metallurgical control. In this study, we had optimal condition and experimented gap bridging capability for butt welding with 2㎜ Al5052 alloys using the filler wire feeder. As the experimental parameters, wire feed rate and wire diameter are considered and then the performance of wire feed is evaluated under various filler wire welding conditions.

• Journal of Welding and Joining
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• v.14 no.1
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• pp.82-91
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• 1996

The maximum butt-joint gap size in $CO_2$ laser beam welding of SAPH steel plates with different thicknesses and its bending formability were studied. In the range of the gap size$\geq$0.1mm, the optimal butt welding speed was faster than that of no gap (air gap) condition. This behaviour was independent on the difference of thickness at any combination. Also, the allowable gap size in steel plates with different thicknesses was larger than with same thicknesses. In the range of $T/T_0$(bead shape) $\geq$ 0.8, good bending formability was obtained at any combination of thickness. The formability was improved by reducing the hardness in weld bead using pre-heating process. Finally, FEM result of the laser beam welded underframe with different thicknesses was compared to that of the conventional spot welded underframe.