Comparative analysis on overlap welding properties of fiber laser and CO2 laser for body-in-white sheets

A systematic study on overlap welding properties of autobody galvanized steel is conducted by using the late-model fiber laser and CO2 laser respectively. The welding joints surface formation, cross-sectional weld shape and mechanical properties of the two types of lasers are compared, and it is analyzed whether dissimilar laser sources would impact the welding quality, so as to control and optimize the craft quality of laser welding automobile body. The results show that under the test conditions, the weld fusion width presents wide at the top and narrow at the bottom and the cross-sections of overlap joints take a “Y” shape by using CO2 laser welding, while those by using fiber laser welding have a shape like “I” which was mean the fusion widths of the upper and lower surface are almost the same. And the anti-shearing force of fiber laser welding joints was stronger due to its larger inter-sheet joint connection width. In addition, under certain conditions, the fiber laser welding could result in more uniform and finer joints, higher strength and hardness, and better mechanical properties.