Numerical Simulation on the Origin of Solidification Cracking in Laser Welded Thick-Walled Structures
Numerical Simulation on the Origin of Solidification Cracking in Laser Welded Thick-Walled Structures
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DOI：
10.3390/met8060406
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发表时间：
2018-06-01
期刊：
影响因子：
2.9
通讯作者：
Rethmeier, Michael
中科院分区：
文献类型：
--
作者：
Bakir, Nasim;Artinov, Antoni;Rethmeier, Michael
影响激光在工业中用于焊接厚结构的主要因素之一是伴随凝固裂纹的过程。这些裂纹多沿焊接方向沿着分布在焊接中心，严重影响焊接构件的安全。在本研究中，为了更好地了解焊接熔池的几何形状，应力分布和凝固裂纹之间的关系，三维计算流体动力学（CFD）模型相结合的热机械模型。采用CFD模型对激光焊接过程中熔池中金属液的流动进行了分析。通过计算流体力学模型得到的熔池几何形状作为热模型中的热源，计算了熔池的温度场和应力发展及分布。计算流体动力学结果表明，在焊缝的中间深度处存在一个鼓包区域，并且两个变窄区域将鼓包区域与顶部和底部表面分隔开。热-机械模拟表明，在凝固裂纹的区域中，在凝固之后在冷却期间直接在横向和垂直方向上存在拉伸应力的集中。
One of the main factors affecting the use of lasers in the industry for welding thick structures is the process accompanying solidification cracks. These cracks mostly occurring along the welding direction in the welding center, and strongly affect the safety of the welded components. In the present study, to obtain a better understanding of the relation between the weld pool geometry, the stress distribution and the solidification cracking, a three-dimensional computational fluid dynamic (CFD) model was combined with a thermo-mechanical model. The CFD model was employed to analyze the flow of the molten metal in the weld pool during the laser beam welding process. The weld pool geometry estimated from the CFD model was used as a heat source in the thermal model to calculate the temperature field and the stress development and distributions. The CFD results showed a bulging region in the middle depth of the weld and two narrowing areas separating the bulging region from the top and bottom surface. The thermo-mechanical simulations showed a concentration of tension stresses, transversally and vertically, directly after the solidification during cooling in the region of the solidification cracking.