In many applications that use high strength steels, structural integrity depends greatly on weld quality. Imperfections and the weld bead geometry are influencing factors on mechanical properties of the welded joints but, especially in the fatigue strength, they cause a great decrease. The proper knowledge of these two factors is important from the nominal stress approach to the fracture mechanics approaches. Studies concerning the profile and imperfections of the weld bead in laser welding for thin plates of high strength steels are scarce. In this work, these two aspects are covered for five series single and double-welded joints, butt joints in a 3 mm thick HSLA steel, welded in a small range of welding parameters. The actual profiles captured with profilometer were modeled with proposed geometric parameters achieving an adequate fit with values of the coefficient of determination ℜ² greater than 0.9000. Description of imperfections includes the distributions of porosity and undercuts. The evaluation of the weld quality, taking as guide the ISO 13919-1 standard determined B and D levels for the welded series while based on the stress-concentrating effect, showed a greater detriment in those series with undercuts and excessive penetration. The analysis of variance validated the results of the different combinations of laser welding parameters and showed, for the factorial experimental design, a more significant effect of the welding speed.

中文翻译：

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HSLA钢薄板中激光对接焊缝轮廓的缺陷和建模

在许多使用高强度钢的应用中，结构完整性在很大程度上取决于焊接质量。缺陷和焊缝几何形状是影响焊接接头机械性能的因素，但是，特别是在疲劳强度方面，它们会导致焊缝的极大降低。从标称应力方法到断裂力学方法，对这两个因素的正确了解很重要。对于高强度钢薄板的激光焊接中焊缝的轮廓和缺陷的研究很少。在这项工作中，这两个方面涵盖了五个系列的单焊和双焊接头，即在3 mm厚的HSLA钢中对接接头，并在较小的焊接参数范围内进行了焊接。²大于0.9000。缺陷的描述包括孔隙率和咬边的分布。对焊接质量的评估以ISO 13919-1标准确定的焊接系列的B和D水平为指导，同时基于应力集中效应，显示出对那些带有咬边和过度熔深的系列而言，更大的危害。方差分析验证了激光焊接参数不同组合的结果，并显示出，对于析因实验设计，焊接速度的影响更大。