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

研究项目的目的是建立一个描述熔池影响的模型，特别是以LDNA方法(非转移电弧激光辅助双丝焊接)为例，重点研究电弧过程中熔体的供应、熔池中的流动和对振荡激光辐射的吸收之间的相互作用。LDNA方法是一种创新的熔覆工艺，通过在两个熔丝电极之间燃烧电弧来实现高熔化速度和低稀释。通过激光对熔体的局部加热确保了涂层与基材的完全连接。了解耦合程度、熔池形成和熔池流动之间的相互作用对于理解应用定义的温度分布对熔体的有意影响以及由此导致的物理性质的局部变化是重要的。该模型将在现有的GMA焊接熔池模型的基础上，通过激光的影响进行扩展，同时考虑到能量和材料供应的修改形式，以实现对熔覆工艺的适应。输入参数为熔滴参数、激光参数和材料的物理性质，输出参数为接缝几何形状和稀释度。利用一种新型的实验装置，测定了激光辐射对过热钢水的耦合程度。通过实验研究确定了熔滴的性质。然后通过实验对所建立的模型进行了标定和验证，并通过数值灵敏度分析和参数量化阐明了输入参数与焊接结果之间的关系。由于调查的基本性质，有可能将所获得的关于故意影响熔体的知识转移到进一步的过程中。

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.