Laser Impact Welding

Laser impact welding (LIW) is a patented technique developed at Ohio State University to join similar and dissimilar combinations of material using the energy generated by high velocity impact. The principle is similar to explosion welding, in that a “flyer plate” is accelerated to velocities exceeding 200 m/sec in a matter of nanoseconds. The kinetic energy resulting from the collision results in the formation of a metallurgical bond.

In LIW, the flyer plate absorbs the energy of the laser, forming a plasma. Under the effect of the rebound pressure of the plasma, the flyer is accelerated over a time interval of a few nanoseconds and collides with the target at high speed. When the collision velocity reaches a critical value, a jet may form. The jet can chemically clean the surface of the flyer and target by removing films, oxides, and other contaminants, which makes it possible for the two materials to approach to within inter-atomic distances. When the clean metal surfaces meet under pressure, metallurgical bonding is possible. One significant advantage of LIW over explosive welding or electromagnetic welding is that the impact can be applied to a precise location (sub-micron precision) over a precise time segment (precision of <10^-5 seconds). In addition, the energy required for LIW is quite low, on the order of a few joules. Therefore, LIW is an appropriate technique to produce welds in applications involving micro/nano interfaces.

To date, preliminary experiments have been conducted on similar and dissimilar combinations of aluminum, titanium, copper, nickel, and iron. The goal is to understand the fundamental bonding mechanisms and to determine if metallurgical reactions that often lead to embrittlement in dissimilar metal systems (i.e. intermetallic formation) can be avoided. Some examples are shown here. Good bonding was obtained in all cases with a characteristic “wavy” bond interface.

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Graduate Student: Huimin Wang (PhD)

Postdoctoral Researcher: Dr. Dejian Liu, Huazhong University of Science and Technology

Collaborator: Prof. Glenn Daehn

1. Y. Zhang, H. Wang, S. Babu, J. C. Lippold, J. Kwasegroch, M. LaHa, and G. S. Daehn. 2011. Feature Article: Collision Welding of Sheet Metals: A Practical and Green Technology, Welding ournal, 90(5):46-51. 
2. H. Wang, D. Liu, G. Taber, J. C. Lippold, and G. S. Daehn, 2012. Laser Impact Welding – Process Introduction and Key Variables, Peer Reviewed Proceedings of the 5^th International Conference on High Speed Forming, Dortmund, Germany, April 2012.
3. D. Liu, H. Wang, J.C. Lippold, and G. Daehn, 2013. Laser Impact Welding for Joining Dissimilar Metal Combinations, submitted to the Welding Journal, Sept 2012.