304不锈钢小功率Nd:YAG脉冲激光-TIG复合焊研究

发布时间：2018-01-22 02:35

本文关键词： 激光-TIG复合焊电弧形态熔池行为复合模式 304不锈钢　出处：《山东大学》2015年硕士论文　论文类型：学位论文

【摘要】：激光-TIG电弧复合焊接作为一种高效优质的焊接新方法,具有焊接速度快、焊接过程稳定、焊接变形小等优点,受到了国内外研究者的重视。相对于大功率激光-TIG电弧复合焊,小功率脉冲激光-TIG电弧复合焊接在充分发挥两种热源优势的基础上,能够进一步降低因电光转换效率低而造成的激光能量的浪费,降低设备成本和焊接生产成本,有利于在实际焊接中进行推广应用,具有较高的实用价值和广阔的应用前景。在304奥氏体不锈钢板上进行堆焊,结合焊接过程图像与电参数同步采集系统,研究了304奥氏体不锈钢小功率脉冲激光-TIG电弧复合焊的电弧形态及导电特性、焊接熔池动态行为及焊缝成形的影响因素及规律,为小功率脉冲激光-TIG电弧复合焊的推广应用提供了理论基础和支撑数据。研究结果表明,脉冲激光产生的少量金属蒸气能够把电弧阳极斑点稳定在激光斑点处,电弧根部发生收缩；激光等离子体与电弧等离子体复合后,引起TIG电弧高温区发生膨胀。当脉冲激光作用到电弧上时,TIG电弧电压稍有升高,分析认为尽管TIG电弧高温区发生膨胀,但其有效导电区发生收缩,这是导致TIG电压升高的原因；脉冲激光消失后,TIG电压又恢复正常。脉冲激光使熔池长度发生周期性的动态变化,但熔池宽度保持不变。热源间距为-0.5mm与0mm时,形成一个熔池,且熔池的形态呈椭圆形；但热源间距在0.5mm-1.5mm范围内,熔池形态为不规则的椭圆形,熔池后方宽度较宽,前方较窄,且激光的作用位置有一部分位于熔池前方的凹陷区：在热源间距为2.5mmm时,熔池分离为激光熔池和TIG熔池。小功率脉冲激光-TIG复合焊焊缝横截面面积是两种热源单独作用下的横截面面积之和的1.5倍左右,达到了1+12的复合效果。对部分焊接工艺参数进行优化,并获得最佳离焦量为0mm、最佳热源间距为0-lmm。研究了复合模式对焊缝成形的影响,YAG-TIG复合模式下获得的焊缝表面成形美观,且熔深大；TIG-YAG复合模式下焊缝表面成形差,熔深浅。小功率脉冲激光-TIG复合热源高速焊接能够有效改善焊缝成形。相对于脉冲激光焊,加入适当的TIG电弧热源后能够消除因斑点重叠率降低而引起的焊缝不连续现象。对于TIG焊,加入脉冲激光束后,能够消除TIG高速焊接产生的驼峰缺陷。认为这是由于脉冲激光加入后,熔池温度升高,降低了熔池的表面张力,且激光作用下产生的熔化金属能够有效地增加熔池前部液态金属厚度,从而避免了驼峰缺陷的产生。
[Abstract]:Laser TIG arc composite welding, as a new welding method with high efficiency and high quality, has the advantages of fast welding speed, stable welding process and low welding deformation. Compared with high power laser TIG arc composite welding, low power pulsed laser TIG arc composite welding takes full advantage of two kinds of heat source. It can further reduce the waste of laser energy caused by the low efficiency of electro-optic conversion, and reduce the cost of equipment and welding production, which is conducive to the practical application of welding. Surfacing welding on 304 austenitic stainless steel plate, combined with welding process image and electrical parameters synchronous acquisition system. The arc morphology and conductive characteristics of 304 austenitic stainless steel low power pulsed laser TIG arc composite welding were studied. The dynamic behavior of weld pool and the influencing factors and rules of weld forming were studied. The theoretical basis and supporting data are provided for the popularization and application of low power pulsed laser TIG arc composite welding. A small amount of metal vapor produced by pulsed laser can stabilize the arc anode spot at the laser spot and shrink the arc root. When laser plasma is combined with arc plasma, the high temperature region of TIG arc expands, and the arc voltage increases slightly when pulsed laser acts on the arc. It is concluded that the effective conductive region of TIG arc shrinks despite the expansion in the high temperature region of TIG arc, which is the cause of the increase of TIG voltage. After the pulse laser disappears, the TIG voltage returns to normal. The pulse laser causes periodic dynamic changes of the weld pool length, but the width of the weld pool remains unchanged. The distance between the heat sources is -0.5 mm and 0 mm. Forming a molten pool, and the shape of the pool is elliptical; But the distance of heat source is between 0.5 mm and 1.5 mm, the shape of molten pool is irregular ellipse, the width behind the pool is wider, and the front is narrower. A part of the laser position is located in the hollow area in front of the molten pool: when the distance of the heat source is 2.5 mm. The welding pool is separated into laser pool and TIG pool. The cross section area of low power pulsed laser TIG composite welding weld is about 1.5 times of the sum of the cross section area of the two heat sources acting alone. The optimum defocusing amount is 0 mm and the optimum heat source spacing is 0 mm. The effect of composite mode on weld forming is studied. The weld surface obtained by YAG-TIG composite mode is beautiful in appearance and deep in penetration. Low power pulsed laser TIG hybrid heat source high speed welding can effectively improve the weld formation, compared with pulsed laser welding. The discontinuity of weld caused by the decrease of spot overlap rate can be eliminated by adding proper TIG arc heat source. For TIG welding, pulse laser beam is added. The hump defect caused by TIG high speed welding can be eliminated. It is considered that the temperature of the weld pool increases and the surface tension of the weld pool is reduced after the pulsed laser is added. The melting metal produced by laser can effectively increase the thickness of liquid metal in front of the molten pool, thus avoiding the formation of hump defect.
【学位授予单位】：山东大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TG457.11

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