Heat sources of hybrid laser–arc welding processes

Fibre laser cutting of thin section mild steel: An explanation of the ‘striation free’ effect

“…The phenomenon of increased absorption of light over a specific range of glancing angles centred around a maximum value at the Brewster angle is well known [7] and a good examination of the subject in the context of laser cutting is provided in [8] and [9]. Figure 11 shows how the absorptivity of a molten iron surface changes with the angle of incidence at glancing angles for light from CO 2 lasers (10.6um wavelength) and fibre lasers (1.07um wavelength) [8,9].…”

“…Figure 11 shows how the absorptivity of a molten iron surface changes with the angle of incidence at glancing angles for light from CO 2 lasers (10.6um wavelength) and fibre lasers (1.07um wavelength) [8,9]. [8] and [9]). …”

“…This approximation is primarily due to the lack of data available in the open literature on the optical properties of molten FeO. However, it can reasonably be argued that the ionic bonding in FeO will result in a band structure that only produces high absorptivities for narrow ranges of frequencies, whereas the frequency dependence of absorptivity of metallic Fe varies more gradually, as can be seen from the Fresnel relations [8,9]. The correlations observed in this work indicate that this approximation is valid.…”