Product Code: ICA11_402

X-Ray Videography for Investigation of Capillary and Melt Pool Dynamics in Different Materials
Authors:
Felix Abt, IFSW, Institut Fuer Strahlwerkzeuge; Baden-Wurttemberg Germany
Meiko Boley, IFSW, Institut Fuer Strahlwerkzeuge; Stuttgart Germany
Rudolf Weber, IFSW, Institut Fuer Strahlwerkzeuge; Stuttgart Germany
Thomas Graf, IFSW, Institut Fuer Strahlwerkzeuge; Stuttgart Germany
Presented at ICALEO 2011

The investigation of capillary and melt pool dynamics in laser welding processes with conventional diagnostic equipment is very challenging. High speed cameras in the visual and infrared spectrum are offering brilliant image quality and outstanding frame rates, but they can only record the behavior of the process surface. Thus only surface phenomena can be observed by these conventional techniques.
To enable insight into the process dynamics phenomena, such as the shape and movement of the capillary or the actual melt flow in the weld bead, X-ray videography is an ideal instrument. However, state of the art high-brightness laser processes require an X-ray system which is capable of imaging capillary diameters of 0.1 mm at frame rates between 1,000 fps and 5,000 fps.
This paper describes different experiments and their results, realized with the high-speed micro focus X-ray system of the IFSW that was described in recent publications. The experiments include different materials like steel, aluminum, copper and bonze, which were welded with focal diameters between 0.1 mm and 0.6 µm with feed rates up to 30 m/min. For the visualization of the fluid dynamics, different tracer materials were tested in order to visualize melt flows with minimum distortion of the welding process.