Open this publication in new window or tab >>2014 (English)In: ICALEO 2014 Congress proceedings, 2014, p. 1-10Conference paper, Published paper (Refereed)
Abstract [en]
Ultra high strength steels are frequently used within the automotive industry for several components. Welding of these components is traditionally done by resistance spot welding, but to get further productivity and increased strength, laser welding has been introduced in the past decades. Fusion welding is known to cause distortions due to built-in stresses in the material. The distortions result in geometrical issues during assembly which become the origin of low joint quality due to gaps and misfits.
U-beam structures of boron steel simulating B-pillars have been welded with laser along the flanges. Welding parameters and clamping have been varied to create different welding sequences and heat input generating a range of distortion levels. The distortions have been recorded dynamically with an optical measurement system during welding. In addition, final distortions have been measured by a digital Vernier caliper. The combined measurements give the possibility to evaluate development, occurrence and magnitude of distortions with high accuracy. Furthermore, section cuts have been analyzed to assess joint geometry and metallurgy.
The results shows that final distortions appear in the range of 0-8 mm. Distortions occur mainly transversely and vertically along the profile. Variations in heat input show clear correlation with the magnitude of distortions and level of joint quality. A higher heat input in general generates a higher level of distortion with the same clamping conditions. Section cuts show that weld width and penetration are significantly affected by welding heat input.
The present study identifies parameters which significantly influence the magnitude and distribution of distortions. Also, effective measures to minimize distortions and maintain or improve joint quality have been proposed.
Finally, transient FE simulations have been presented which show the behavior of the profiles during the welding and unclamping process.
Keywords
Welding, laser, steel
National Category
Production Engineering, Human Work Science and Ergonomics Manufacturing, Surface and Joining Technology Metallurgy and Metallic Materials
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-7262 (URN)
Conference
ICALEO – 33rd International congress on applications of lasers & electro-optics
Funder
VINNOVA
2015-01-092015-01-092018-08-12Bibliographically approved