Experimental Techniques to Cut and Weld Copper by Laser - A Review

Single pass hybrid laser–MIG welding of 4-mm thick copper without preheating

“…At last, 4 increasing of weld width would necessarily result in larger transversal tensile stress in FZ. 5 Therefore, the length of crack increased with the increasing of laser power, as shown in Fig. 5d, e 6 and f. Fig.…”

“…distance. It is shown in the figure that when laser-arc distance was approximately 3 mm, crack 5 susceptibility was higher, whereas the number of pore was less, which might primarily due to that 6 thermal efficiency of welding process was relatively higher when laser-arc distance was about 3 7 mm. 11 In the previous subsections, it was argued that the dependence of defects on welding 12 condition could be related to that thermal efficiency or total heat input changed with the variation of 13 welding condition.…”

“…As mentioned above, the processing window of hybrid BOP welding of copper was rather 4 narrow due to the large solidification shrinkage rate and the high thermal conductivity of copper. 5 Therefore, it is hard to give consideration to both porosity susceptibility and crack susceptibility in 6 the case of BOP welding and it is necessary to find a substitute looking both issues. In this 7 subsection, I-groove butt welding with a preset gap was tried on 4-mm thick copper.…”

“…It was 37 reported that the absorptivity of copper for a 1000-nm wavelength infrared laser was about 5% at 1 room temperature, whereas after being heated to near its melting point, the absorptivity of copper 2 for 1000-nm infrared laser reached approximately 14% [3] . The low laser absorptivity of copper for a 3 1000-nm infrared laser led to that the stability and repeatability of laser beam welding process was 4 highly sensitive to the surface conditions of copper work piece, such as coarseness and amount of 5 oxide [3] . To determine a method to apply laser beam to copper welding, researchers worldwide have 6 spent much effort and made numerous attempts.…”

“…To determine a method to apply laser beam to copper welding, researchers worldwide have 6 spent much effort and made numerous attempts. Ni coating, Cr coating, granite coating, and oxide 7 layer have been prepared on copper's surface to improve the thermal efficiency of laser welding 8 process [4,5] ; O 2 [6,7] and N 2 [8] have been added in auxiliary gas to improve the laser energy coupling 9 efficiency of copper welding process; stainless steel powder has also been added into molten pool in 10 copper welding process to improve laser energy coupling efficiency [9] ; laser systems with 11 ultra-high power were used by some researchers for copper welding [10,11] . Recently, the rapid 12 development of disk laser and fiber laser technologies facilitated the progress of laser beam welding 13 technology for copper.…”