Figure 3
Dynamic evolution of the melt pool in laser powder bed fusion processes of Ti-6Al-4V. (a) X-ray images of melt pools in the metal base at t = 0, 200, 400, 600, 800, and 1000 µs, respectively. The blue dashed line marks the boundary of the cavity or depression zone, and the red dashed line indicates the liquid-solid interface. The power and size of the laser beam are 520 W and ~220 µm (1/e2), respectively. The laser is turned ON at t = 0, and continues to heat the sample till t = 1000 µs. The powder particle size is in the range of 5–45 µm, and the powder layer thickness is ~100 µm. (b–d) Development of the melt pool size and geometry as a function of laser heating time under two different laser power conditions: (b) depth, (c) aspect ratio (depth/width), (d) nominal area. The inset to (d) shows a steady-state melt pool configuration at the time indicated by the solid green square. All the scale bars in (a) and in the inset to (d) are 100 µm.
