Effect of alloy element on weld pool dynamics in laser welding of aluminum alloys

Miyagi, Masanori*; Hongze, W.*; Yoshida, Ryohei*; Kawahito, Yosuke*; Kawakami, Hiroshi*; Shobu, Takahisa  

The behavior inside the metal during laser welding is very important because it greatly affects the material strength, defect generation, and so on. In this study, weld pool dynamics in laser welding of various series of aluminum alloys were investigated by the synchrotron radiation X-ray phase contrast imaging system. The experimental results showed that metal irradiated by laser was evaporated immediately, which generated the keyhole. Then metal surrounding the keyhole was melted gradually with the heat from keyhole. The growth rate of keyhole depth had a positive linear correlation with the total content of low boiling temperature elements (TCE), so did the keyhole depth and diameter at the stable stage. Then, by repeating the experiment, we succeeded in quantifying the effect of alloying elements on the dynamics of the weld pool in laser welding of aluminum alloys.