Application and Modeling of Laser Beam Submerged-Arc Hybrid Process

在第一阶段的研究中，开发了CO2激光器和固体激光器的激光埋弧复合焊接工艺，并实现了这两种类型的复合焊头。同时，建立了混合等效热源模型，作为模拟激光埋弧复合焊接过程的基础，采用固体激光器的新方向，大大提高了焊接过程的重复性和工艺稳定性。这主要是因为波长短得多的激光不太容易形成激光诱导的等离子体，而使用二氧化碳激光往往会导致工艺不稳定。使用这两种工艺连接，已在板厚达40 mm的板材上进行了具有高度可接受质量的焊接。除了目测和评定内部焊缝质量外，还测定了内部焊缝的力学性能。收集的硬度和抗拉强度结果在整个焊缝深度内是一致的，特别是在SA占优势的上部和更深的LB型占优势的区域之间。然而，缺口冲击试验的结果在焊缝内存在很大差异。而内部的，以LB为主的区域大多提供非常高的冲击功，而较高的，SA占优势的区域只承受较低的冲击能量，甚至低于给定线-焊剂组合的值。在研究项目的第三年，将继续探索各种线材-焊剂组合或参数优化是否能导致缺口冲击能和其他技术性能的最优化和均匀化。此外，还将对熔池内的材料迁移问题进行实验研究。这可能为了解混合流动区内的流动状况奠定基础。

In the first phase of the research project, the laser beam submerged arc hybrid welding process has beendeveloped for the CO2-laser as well as the solid-state laser.For both types hybrid welding heads have been realised. In parallel, a model of the hybrid equivalent heatsource has been developed as base for the simulation of the laser beam submerged arc hybrid weldingprocess.With the new orientation towards the use of solid-state lasers, the reproducibility and process stability wasgreatly enhanced. This was mainly because the much shorter laser wavelength is less prone to laser inducedplasma formation that often led to process instabilities with the use of the CO2-laser.With both process variants connections welds with highly acceptable quality have been performed on platethicknesses up to 40 mm. Beside visual testing and assessing the inner weld seam quality, mechanicalproperties have been determined.The gathered results on hardness and tensile strength were in the expected ranges and consistent over thewhole depth of the weld seams, especially between the upper, SA-dominated and the deeper, LB-dominatedareas.The results of the notch impact tests however differed strongly within the weld seam. While the inner,LB-dominated areas give mostly very high values of impact energy, the upper, SA-dominated areas only bearlow impact energy, even lower than the given values for the wire-flux combination.In the third year of the research project, it stand to be explored whether a varation of wire-flux combinations orparameter optimisations can lead to optimised and homogenised values of notch impact energy as well as theother technical properties. In addition, there will be experimental research on the topic of material transportinside of the molten pool. This may lay the foundation on the understanding of the flow conditions inside of thehybrid process zone.