レーザ溶接したアルミニウム合金のポロシティ生成に及ぼすシールドガスの影響

概要

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Aluminum alloys. have been bead-on-plate welded with a CO_2 laser using shielding gas of Ar. The effect of shielding gas on the porosity formation during the laser welding has been investigated by varying a gas flow rate and a nozzle design. As for the case where a single-type coaxial nozzle is used, the amount of porosity abruptly decreases when the gas flow rate changes from 15 to 20 L/min. Moreover, the shielding gas is rotated and impinged on the laser focus using a double-type coaxial nozzle, the amount of porosity considerably decreases. The CFX-5 code, a computer program for the solution of three-dimensional transient fluid flow, has been applied to the analysis for shielding gas and metal vapor flows during the laser welding. The experimental results is discussed in connection with the results of calculation.
2005-09-30