Measurement of Beam Energy Absorption in CO2 Laser Beam Welding.

Abstract

Rate of absorption of CO2 laser beam energy during bead-on-plate welding of SM400 mild steel plate was measured. A 10 kW industrial CO2 laser welding equipment was used in this study.In the first part of the experiments, bead-on-plate welding was made on a water-cooled steel plate placed in a welding jig made of acrylic plastics. The surface of the steel plate was machine-finished. The laser beam energy absorbed into the steel plate was calculated from the measurements of the inlet and the outlet water temperatures, the water flow rate and the beam-on time.Rate of absorption was calculated as the ratio of the absorbed beam energy to the total beam power.In the second part, bead-on-plate welding was carried out on either a machine-finished, a paint-coated on machine-finished or a ground-finished steel plate. Absorption was also evaluated.In the third part, heat conduction loss to the acrylic welding jig was evaluated and found to be approximately 5%. The results of measurements and calculation were reported and discussed.It was estimated in this study that absorption of CO2 laser beam energy during bead-on-plate welding of a mild steel plate at a laser power of 10 kW was in the range from 30 to 50%.

Modeling the effect of processing parameters on temperature history in Directed Energy Deposition: an analytical and finite element approach

“…As shown in Figure 5 an increase in laser power leads to an increase in the temperature. This finding has already been supported by previous studies (Chen et al , 2017; Shida and Terauchi, 1996; Moradi et al , 2020).…”

“…In addition to investigating laser power, the effect of power absorption efficiency on temperature history is also studied in this section and presented in Figure 6. Power absorption efficiency is defined as the ratio of total heat to incident energy (Shida and Terauchi, 1996). As laser energy cannot be fully absorbed within a constant depth (Chen et al , 2017), values of 0.4, 0.6 and 0.8 were selected for this research.…”

“…As laser energy cannot be fully absorbed within a constant depth (Chen et al , 2017), values of 0.4, 0.6 and 0.8 were selected for this research. An increase in absorption efficiency means that the laser beam or heat source has more time to melt the powder, which can be achieved by controlling laser scanning speed, laser power, laser focus (Shida and Terauchi, 1996), laser wavelength, energy density (Yang et al , 2018; Kumara et al , 2019), material state and local phase fraction. The developed model shows that an increase in power absorption efficiency increases the temperature history (Kawahito et al , 2013).…”

Relationship of laser absorption to keyhole behavior in high power fiber laser welding of stainless steel and aluminum alloy

“…High power and the corresponding power density can generate a deep keyhole in a molten pool easily, and such a high-power beam is expected to be absorbed sufficiently. Concerning conventional lasers, a large number of studies have been made on laser absorption by Shida et al (1999), Sakamoto et al (2003), Miyamoto et al (1986), Stern (1990), Yamada et al (1999), Dausinger (1990) and Arata et al (1971). It was reported by Shida et al (1999) that mild steel absorption for carbon dioxide (CO 2 ) laser in bead-on-plate welding were changeable from 72 to 87% depending upon welding conditions.…”

“…Concerning conventional lasers, a large number of studies have been made on laser absorption by Shida et al (1999), Sakamoto et al (2003), Miyamoto et al (1986), Stern (1990), Yamada et al (1999), Dausinger (1990) and Arata et al (1971). It was reported by Shida et al (1999) that mild steel absorption for carbon dioxide (CO 2 ) laser in bead-on-plate welding were changeable from 72 to 87% depending upon welding conditions. Sakamoto et al (2003) shows that coupling rates were extremely improved from 20 to 60% when the penetration geometry changed from a heat-conduction to a keyhole type with an increase in laser power from 0.6 to 3 kW in YAG laser welding of aluminum alloy.…”