<i>In-situ</i> x-ray phase contrast observation of the full penetration spot welding on limited aluminum material thickness

The laser-spot welding process of aluminum alloy 1050A with a limited thickness is observed the x-ray phase contrast method to investigate melt dynamic especially when penetrates material. investigated two different wavelengths laser beam source: 515 and 1030 nm influence absorptivity. progressively material during spot-welding until reaching bottom side lower material, so-called “lens-like” appears at due surface tension. At comparable intensity value, oscillation driven by expansion vapor capillary. This occurs inside directly above melt. shape expanded determines volume as well geometry resulting volume. Furthermore, transition from heat conduction mode keyhole defocusing for source wavelength. given variation, clear difference between either method.