Investigation of Laser Hybrid Welding Process Using a Self-Consistent Multiphysics Model with Experimental Verification

Michigan State University, East Lansing MI

Investigators

Abstract

National Science Foundation Proposal Number: CTS-0425217 Principal Investigator: Hyungson Ki Affiliation: Michigan State University Proposal Title: Investigation of laser hybrid welding process using a self-consistent multiphysics model with experimental verification Abstract Recently, laser hybrid welding has invoked a great deal of interest due to its unique benefits. However, the study of laser hybrid welding is still in its infancy, and even the associated physics are not clearly understood. In fact, a very wide range of physical phenomena occur during the process. Similar to other fusion welding methods, complex melt flows induced by strong vaporization and the thermocapillary effect, heat transport with phase transformations, dynamic free surface evolution, and microstructure evolution form the kernel of the process. However, what makes laser hybrid welding a unique and more challenging process is the complex interaction between laser beams, electric arcs, and plasmas. This extreme process environment caused by their interaction prohibits direct observation and measurement of the welding process. In addition, modeling of this process requires a multidisciplinary and multiphysics approach. This proposal is to develop a laser hybrid welding model especially focusing on the laser-plasma-arc interactions and their effects on microstructure/weld quality predictions. It is also proposed to perform direct visualization experiments using a high-speed CCD camera, called the Reflective Topography. This method will be improved using image processing techniques. Weld microstructure will be investigated using the Scanning Electron Microscopy to verify the model and provide inputs to the model. The Reflective Topography method will be a valuable tool since it enables a direct observation and measurement during the process. This research will be a very extensive and comprehensive work and will help deploy this technology in industry for very challenging joining problems. A better understanding of the process through a systematic numerical and experimental study will aid in manufacturing and will justify more research aimed at developing more efficient and economical hybrid welding systems. This study will be especially beneficial to the shipbuilding industry and automobile industry. The research is being supported jointly by the Thermal Transport and Thermal Processing Program of the Division of Chemical and Transport Systems and the Materials Processing and Manufacturing Program of the Division of Design, Manufacturing and Industrial Innovation.