Product Code: ICAL06_P519

The Use of Overlapping Nd:YAG Laser Spot Welds to Butt Weld Steelite, a Metal Polymer Laminates
Authors:
Heather Gower, NIMR/ TU Delft; Delft Netherlands
Ian Richardson, NIMR / TU Delft; Delft Netherlands
Raph Pieters, NIMR / TU Delft; Delft Netherlands
Presented at ICALEO 2006

Metal polymer sandwich structures are gaining in importance, especially in the transport industry where lightweight and high stiffness are particularly attractive. To date joining of these laminates has been limited to riveting, splicing or adhesive bonding, all of which require an overlap joint which is not always desirable. This paper presents a new method where overlapping laser spot welds are used to butt weld Steelite, a steel-polypropylene-steel sandwich structure produced by Corus. Laser spot welding was selected as a low heat input process to confront the unique challenges associated with the polymer layer, upon welding gaseous degradation products form which can disrupt the weld pool. Autogenous butt welds were created successfully in the 0.12 mm thick skin layer of Steelite. Cross sections of the welds show an increase in width of full penetration welds at the metal-polymer interface. The degradation of the polymer layer is less severe with a lower energy input; however cracking is more prevalent, possibly due faster cooling rate and entrapment of degradation products. At higher heat input, complex fluid flow patterns emerge and despite some polymer degradation, good quality welds can be achieved. The successful welding of the skin layers of Steelite provides opportunities to further develop techniques for the joining of metal polymer laminates.