Product Code: ICAL06_805

Experimental and Computational Investigation of Fusion Zone Geometries during Autogenous Keyhole Mode Laser Welds
Authors:
Rohit Rai, Dept. of Materials Science and Engineering, The Pennsylvania State University; State College PA USA
Richard Martukanitz, Laser Processing Division, Applied Research Laboratory, The Pennsylvania State University; State College PA USA
Shawn Kelly, ARL, The Penn State University; State College PA USA
Tarasankar DebRoy, Dept. of Materials Science and Engineering, The Pennsylvania State University; State College PA USA
Presented at ICALEO 2006

In recent years it has become known that the hybrid welding processes involving simultaneous use of both a laser and an arc welding systems may alleviate some of the difficulties encountered in single heat source operations involving either a laser beam or an arc. Here we report a detailed experimental and numerical modeling study of the weld geometry, cooling rate and solidification characteristics of the ASTM A131 structural ship steel fabricated by the three welding processes, i.e., the laser beam, arc and laser beam-arc hybrid welding processes. In order to quantitatively understand the heat transfer, fluid flow and solidification processes, a mathematical model involving numerical solution of the equations of conservation of heat mass and momentum in three dimensions was developed. The model considered formation of a keyhole, Marangoni convection at the weld pool surface and electromagnetic force field due to electric current. The computed results provide a detailed description of the temperature and velocity fields in the weldment, the shape and size of the keyhole, the geometry of the fusion zone and various solidification parameters. The effects of different distances between the two energy sources, and different ratios of heat input from the two sources were examined. A comparison of the experimental and the computed results show that the simulated results can be used to determine both the optimum distance of separation of the two heat sources and their relative magnitudes.