Achieving fundamental understanding about the influencing of the melt pool by laser radiation in the laser assisted double wire welding with nontransferred arc (LDNA).

点击翻译按钮获取中文摘要

The aim of the research project is to create a model for describing the influencing of the melt pool, with particular emphasis on the interaction between the melt supply by the arc process, the flow in the melt pool and the absorption of the oscillating laser radiation, using the example of the LDNA method (laser assisted double wire welding with nontransferred arc). The LDNA method is an innovative cladding process which achieves high melting rates with low dilution by burning an arc between two melting wire electrodes. A local heating of the melt by means of a laser beam ensures a full connection of the coating layer to the base material. The knowledge of the interaction between coupling degree, melt pool formation and melt pool flow is important for the understanding of the deliberate influencing of the melt by the application of a defined temperature profile and the resulting local changes of the physical properties.In order to obtain this knowledge, simulative and experimental investigations are carried out in this project. The model, which is to be developed, is based on the already existing melt pool model for GMA welding and extends it by the effect of the laser, while taking into account the modified form of the energy and material supply in order to achieve an adaptation to the cladding process. The input parameters are the molten droplet parameters, the laser parameters and the physical properties of the materials and the output parameters are seam geometry and dilution. A novel experimental setup is used to determine the coupling degree of laser radiation on overheated molten steel. The properties of the molten droplets are also determined by experimental investigations.The developed model is then calibrated and validated by experimental trials, and the relationship between the input parameters and the welding results is clarified by a numerical sensitivity analysis and parameter quantification. Due to the fundamental character of the investigation, it is possible to transfer the gained knowledge on influencing the melt in a deliberate manner to further processes.