从陆上空气中气体保护焊接和水下湿法气体保护焊接的共性与特性入手,考虑水下湿法焊接热过程的特点, 应用有限元软件SYSWELD,建立了水下湿法药芯焊丝熔化极气体保护电弧焊接(FCAW)热过程和温度场的数值分析模型,计算了4组工艺参数下焊缝成形与形状尺寸的典型数据, 并与实验结果进行了对比,验证了所建立的热源分布模式和水下湿法焊接有限元模型能够模拟水下电弧的作用特点和水下湿法焊接接头的成形特点.实验结果表明, 水下FCAW焊接焊缝成形的规律与常规的熔化极气体保护电弧焊接相似,但同样焊接参数下水下焊接的焊缝更窄, 熔深更大.

Underwater wet flux-cored arc welding (FCAW) has great potential prospects of wide application in ocean engineering due to its easiness of automation and high weld quality. However, the thermal process of underwater wet welding is more complicated: the arc energy distribution is more concentrated in high-pressure environment of underwater, the convection heat transfer coefficient of the weldment under water is much larger than that in air. This study focuses on establishing the numerical model for analyzing the thermal process and the temperature field in underwater wet FCAW by using the FEM software SYSWELD. Both the generalities and peculiarities of the conventional GMAW (gas metal arc welding) in air and underwater wet FCAW processes are taken into consideration, especially the two remarkable characteristics of underwater wet welding, i.e., the water compressing action to the arc, and the enhanced heat losses caused by the surrounding water. Based on the calculated temperature profiles, the weld bead shape and sizes are predicted in underwater FCAW, which lays the foundation for the process optimization. It is found that under 4 groups of typical welding conditions the calculated weld bead dimensions are in agreement with the experimental ones, which validated the energy distribution pattern of the heat source and the numeric model for underwater wet welding. Experiments showed that the weld bead was thinner and deeper in underwater wet welding than that in conventional GMAW under the same welding parameters, while the variation regularity of weld bead profile is similar.