GMAW工艺仰焊咬边缺陷的研究分析与控制

Research,analysis and control of undercut defects on GMAW process overhead welding

对电站锅炉膜式壁管排鳍片与管子角焊缝采用熔化极气体保护焊(GMAW)仰焊位置易产生咬边缺陷进行了试验研究,根据不同材料焊接生产出现咬边的几率,对材料成分进行了统计与分析研究。仰焊时由于重力因素会加剧熔化金属下坠,使熔化金属脱离焊趾而流向熔池中心,导致仰焊更容易产生咬边缺陷。结果表明,焊接速度是影响产生咬边的关键因素,通过降低焊接速度可以有效地减小和消除咬边缺陷;Mn/S比较低的材料,产生咬边缺陷的几率较高,焊接时应严格控制焊接速度。

Test was made in order to research the formation cause of the undercut defects on GMAW overhead welding for power boiler membrane fin to tube welds,based on the probability of undercut occurrence on welding of different materials,made a statistics and analysis for material chemical composition.The gravity force will intensify the sag of molten metal during overhead welding,which drive the molten metal move to the center of weld pool,and cause lack of molten metal in the weld toes leading to undercut defects.The research shows that welding speed is a key factor to affect the occurrence of undercut,it will be helpful to decrease and eliminate the undercut defects via reducing the welding speed.the possibility of undercut occurrence is higher if the Mn/S rate is lower in the material during welding,welding speed should be controlled strictly during welding.