Abstract Scope |
Material flow behavior and welding defects formation inside the melted domain of welding and additive manufacturing (AM) processes are key information to reveal the underlying mechanism of weld pool formation and the relation to the metallurgy phenomena and microstructure formation. However, these phenomena occur at an extremely hard condition to observe owing to the high arc plasma intensitive at several thousand temperatures in a short time scale. Therefore, the traditional approaches using high-speed video cameras (HSVCs) is impossible to utilize. For solving this trouble, several experiment groups have developed new X-ray synchrotron image systems that can detect clearly molten pool formation and revolution of keyhole in material processes such as: laser welding and AM. The results have enormous value to explode a new era of observation technology for welding and AM. However, these systems have presented the two-dimensional images with only one X-ray source and one HSVC. As a result, the acquired information is mainly on the keyhole revolution and spatter defects behavior. However, the nature of welding and AM processes is not only these phenomena, it is more important to show and discuss the molten flow thermodynamic during welding period. In order to overcome this issue, we have developed the first X-ray radiography beam observation system including two parts. Each part includes one X-ray beam source and one HSVC, which is set up at two individual angles. Both parts are connected synchronously. Both X-ray beam lines are controlled to intersect at the center point of the melted domain. As a result, three-dimensional images of weld pool and material flow inside the melted domain are detected. With support of other softwares, velocity, acceleration, and movement of molten material flow can be discussed in detail. |