Abstract
Controlling part-to-part gaps is a crucial task in the laser welding of galvanized steel sheets for ensuring the quality of the assembly joint. However, part-to-part gaps are frequently non-uniform. Hence, elevations and depressions from the perspective of the heading direction of the laser beam always exist throughout the gap, creating ascending, descending, and flat travelling paths for laser welding. In this study, assuming non-uniform part-to-part gaps, the effects of welding direction on the quality of the joint of galvanized steel sheets—SGARC440 (lower part) and SGAFC590DP (upper part)—were examined using 2-kW fiber and 6.6-kW disk laser welding systems. The experimental analysis of coupon tests confirmed that there is no statistically significant correlation between the direction of welding and weld pool quality if the gap exceeds the tolerable range. However, when the gap is controlled within the tolerable range, the welding direction can be considered as an important process control variable to enhance the quality of the joint.
Highlights
From the perspective of automotive body-in-white assemblies, laser welding has many desirable features such as high joining speed, excellent repeatability, and non-contact single-sided access, resulting in a greater degree of freedom in car body design
When the gap is controlled within the tolerable range, the welding direction can be considered as an important process control variable to enhance the quality of the joint
Tight part-to-part gap control is required to ensure the assembly joint quality of the galvanized steel sheets; these sheets are characterized by the lower evaporation point of Zn (906 ̋ C) than the melting point of Fe (1538 ̋ C)
Summary
From the perspective of automotive body-in-white assemblies, laser welding has many desirable features such as high joining speed, excellent repeatability, and non-contact single-sided access, resulting in a greater degree of freedom in car body design. Laser welding is yet to be widely and successfully used, especially for joining of complex galvanized steel parts in lap-joint configurations [1], for which conventional joining methods such as resistance spot welding are generally employed. Benyounis et al [2] identified the importance of laser power, focal position, and welding speed on the assembly joint’s quality such as heat input and weld bead geometry (i.e., penetration depth, widths of welded zone, and heat-affected zone). Wu et al [3] confirmed that there is a statistically significant correlation between a joint’s quality (i.e., welding penetration and the width of a weld seam) and laser power and welding speed. The vaporized zinc gas hampers the formation of stabilized keyholes and often causes serious weld defects such as porosity, spatter, intermetallic brittle phases, and discontinuities formed by zinc vapor entrapment in the welding joints [4]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
