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首页> 外文会议>Conference on Laser Materials Processing Vol.85f: Welding and Modeling, Nov 16-19, 1998, Orlando, FL USA >Study on prevention of welding defects for thick plates with high power CO_2 laser
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Study on prevention of welding defects for thick plates with high power CO_2 laser

机译：大功率CO_2激光预防厚板焊接缺陷的研究

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摘要

The authors have examined proper welding condition which enclosed good weld beads in terms of welding appearance for full penetration welding. For CO_2 laser welding of large output, it is generally known that porosity may occur in the weld bead when a deep penetration welding in single pass is performed in the ambient atmosphere. Welding defects mainly including porosity also occur more frequently with increase of plate thickness even though in the case of using proper welding condition. In order to spread laser welding generally, porosity is one of the most important problems to be solved. It is thought that formation mechanism of porosity is expressed as follows. Bubbles are generated mainly at the bottom of keyhole, which are trapped in molten metal during floating up and remain as porosity in metal. In this context, to reduce welding defects in welded bead, the authors paid attention to the following two conceptions; the first is that long heat input time would enable to delay beginning of molten metal solidification; the second is that molten metal could be fluidified smoothly by changing direction of recoil pressure. The authors adopted use of twin spot condensing system and improvement for the radiation angle of laser to test piece to accomplish these conception. Twin spot welding was the method of welding with two spot lasers which were condensed two laser beams which were divided from an uncondensed laser beam so that heat input increased in spite of decrease of penetration depth. Forehand welding was performed using a method of inclined laser radiation so that molten metal could be fluidified smoothly by changing direction of recoil pressure. In this report, the authors discuss in detail the prevention of welding defects which are generated by mainly porosity for thick plates.
机译：作者已经检查了合适的焊接条件，该条件在全外观焊接的焊接外观方面封装了良好的焊缝。对于大功率的CO_2激光焊接，众所周知，当在环境气氛中进行单道次深熔焊时，可能在焊道中产生气孔。即使在使用适当的焊接条件的情况下，主要包括气孔的焊接缺陷也随着板厚的增加而更频繁地发生。为了一般地散布激光焊接，孔隙率是要解决的最重要的问题之一。认为气孔的形成机理表示如下。气泡主要在锁孔的底部产生，气泡在漂浮过程中被困在熔融金属中，并以孔隙形式保留在金属中。在这种情况下，为了减少焊缝中的焊接缺陷，作者注意以下两个概念：首先，较长的热量输入时间将延迟熔融金属凝固的开始。第二是通过改变反冲压力的方向可以使熔融金属平稳地流化。作者采用双点聚光系统，并通过改进激光的辐射角来实现测试件的设计。双点焊是用两个点激光进行焊接的方法，该两个点激光会聚了两个激光束，从非会聚激光束中分离出了两个激光束，尽管穿透深度减小了，但热量输入却增加了。使用倾斜激光辐射的方法进行正手焊接，以便可以通过改变反冲压力的方向使熔融金属平稳地流化。在这份报告中，作者详细讨论了预防焊接缺陷的方法，这些缺陷主要是由厚板的孔隙引起的。

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