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

该研究项目的目的是创建一个模型来描述熔池的影响，特别强调电弧过程中的熔体供应、熔池中的流动和振荡激光辐射的吸收之间的相互作用，并以LDNA方法为例（激光辅助非转移电弧双丝焊接）。LDNA方法是一种创新的包层工艺，通过在两个熔点电极之间燃烧电弧，实现高熔化率和低稀释。通过激光束对熔体进行局部加热，确保涂层与基材完全连接。了解耦合程度、熔池形成和熔池流动之间的相互作用，对于理解通过应用确定的温度分布对熔体的故意影响以及由此导致的物理性质的局部变化是重要的。为了获得这些知识，本项目进行了模拟和实验调查。待开发的模型是在已有的GMA焊接熔池模型的基础上，通过激光的影响对其进行扩展，同时考虑到能量和材料供应的修改形式，以实现对熔覆过程的适应。输入参数为熔滴参数、激光参数和材料的物理性质，输出参数为焊缝几何形状和稀释度。采用一种新的实验装置来测定激光辐射对过热钢液的耦合度。通过实验研究确定了熔滴的性质。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明确了输入参数与焊接结果的关系。由于研究的基本特征，有可能将所获得的关于以慎重的方式影响熔体的知识转移到进一步的工艺中。

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.