Modeling penetration and free surface depression during high current arc welding

摘要

The aim of this research is to model,understand and predict the physics of the physics of the weld pool during high current arc welding,including molten metal flow,surface effects,and droplet impingement when appropriate.Particular emphasis is given to the spray transfer mode in GMAW,which is the most widely used in industry for welding of thick sections and high productivity applications.For the high current regime (generally above 250 A), the maximum free surface depression can be comparable to weld penetration.In this situation,parts of the weld pool behave like a thin film,and phenomena such as a "dry bottom" of the weld pool,or gysteresis cycles in weld penetration are observed.These effects cannot be explained solely on the basis of surface deformation under arc pressure.We are currently investigating the influence of Marangoni flows in the formation of this thin film.The applications of this work include control of weld defect formation, the development of control algorithms(e.g. training a neural network),the optimization of welding processes,the selection of materials for welding,and overall process quality improvement.Patricio Mendez started this research topic originally under the guidance of Prof.Szekely,with whom be worked for two years.