大厚板双面双TIG电弧打底焊熔池成形特性

采用视觉图像监测法对新开发的双面双TIG电弧错位同步打底焊熔池成形特性进行了研究.结果表明,根部预留间隙是保证打底焊根部熔合的有效措施,可以实现大厚板不清根焊接.脉冲TIG焊是大厚板打底焊的优选方法,峰值期间电弧熔化能力强,坡口根部两侧边缘熔化良好.基值期间熔池迅速凝固,防止了下淌.双TIG电弧错位同步打底焊时,后电弧的加入导致两弧之间工件高温区增加,前电弧熔池拉长.焊缝宏观金相显示母材充分熔化,没有侧壁未熔合,焊缝正表面成形圆滑过渡,没有气孔、裂纹、夹渣、咬边等成形缺陷.

Characteristics of pool formation in backing weld for large and thick plates using double-sided double TIG arc welding

With a new developed misplacing and synchronizing double-sided TIG backing welding technique,the characteristics of welding pool formation are invesitgated by means of monitoring visual images.The experiment results show that presetting welding gap is an effective approach to ensure the root fusion,which makes it possible to weld large and thick plates without back chipping.The pulsed TIG welding is an optimal choice for backing welding of large and thick plates.Both sides of the groove root melt during the peak current period due to the strong melting ability of the arc.The welding pool rapidly solidifies during the base current period,preventing the dropping of welding pool.During misplacing and synchronizing double-sided backing welding,the rear arc leads to an increment of the high temperature area in the workpiece and elongation of the front pool.The macrograph of the weld shows that the base metal sufficiently melts and the lateral wall fuses well.The weld surface is smooth with no pores,cracks and inclusions.