2009 Volume 50 Issue 7 Pages 1649-1654
A new welding technology called “plasma arc weld bonding” was designed by combining the plasma arc welding and adhesive bonding process in the lap welding of magnesium alloy. During the “plasma arc weld bonding” process, the major difficulty was the presence of porosity in the welding joint. This paper analyzed the formation mechanism of pores and the effect of welding parameters on pores behaviors during plasma arc weld bonding process of magnesium alloy by optical microscopy and electron probe microanalysis. The results showed that it easily formed a lot of pores in joint because of the existence of adhesive layer. The decomposition of adhesive in both the sides of welding seam was the main cause for the formation of pores. The regular-shape pores were formed by CO and CO2, and the anomalous-shape pores were formed by the low molecular weight hydrocarbons. The pores behaviors were affected evidently by the heat input, and the favorable joint could be obtained when the heat input was about 396 kJ/m.