Study on Reduction of Residual Stress of Welding Joint Using Vibration

利用振动降低焊接接头残余应力的研究

基本信息

批准号：
05650250
负责人：
AOKI Shigeru
金额：
$ 1.47万
依托单位：
Tokyo Metropolitan College of Technology
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

Welding is widely used for construction of many structures. There exists residual stress near the bead because of locally given heat. Tensile residual stress on the surface degrades strength for cumulative damage. Some reduction methods of residual stress were presented. In this paper, a new method is proposed in which vibrational load is used during welding operation and an analytical method for the proposed method is presented. Advantage of this method is that vibrational load is generated by a small shaker. This method is expected to be a practical one.First, reduction of residual stress is examined experimentally. Two plates of 100mm width are used. Two plates of rolled steel for general use (JIS SS400) are supported on the supporting devices by bolts and shaken by a small shaker during welding. Specimens are butt welded using automatic CO_2 gas shielded arc welding machine. Groove is V-shaped. Welding is completed through one pass. Excitation frequency is chosen as 60Hz which is t … More he fundamantal natural frequency of specimens before welding. In order to examine reduction effect of residual stress at non-resonane frequency, excitation frequency is also chosen as 100Hz. Residual stress is measured by removing the quenched scale chemically and using a parelelled beam X-ray diffractometer with a scintillation counter.From the experiment, it is found that on the bead, tensile residual stress is significantly reduced when vibrational load is acting during welding. At points near the bead, residual stress is also reduced. At points far from the bead, compressive residual stress tends to be tensile. Residual stress decreases as the amplitude of excitation increases.Next, an analytical method for reduction of residual stress by the proposed method is examined. It is obvious that reduction of residual stress is caused by local plastic deformation because initial residual stress is great and nearly equal to yielding stress. Thus, an analytical model which consists of mass and preloaded spring with elasto-plastic characteristic is used. From the analysis, it is found that reduction rate of residual stress increases as the amplitude of excitation increases. Thus, effectiveness of the proposed method can be demonstraited by experimnet and analysis. Less

焊接广泛应用于许多结构中，由于表面局部存在的残余拉应力会导致累积损伤而导致焊缝附近存在残余应力。本文提出了一种新的减少残余应力的方法。提出了在焊接操作过程中使用振动载荷的方法，并提出了该方法的分析方法，该方法的优点是振动载荷是由小型振动台产生的。首先，减少残余应力采用两块100mm宽的板材（JIS SS400），用螺栓支撑在支撑装置上，并在焊接时用小型振动台对试件进行对接焊。弧焊机的坡口是V形的，通过一次焊接完成。励磁频率选择为基本固有频率。为了检验非共振频率下残余应力的降低效果，通过化学去除淬火氧化皮并使用带有闪烁的平行光束X射线衍射仪来测量残余应力。实验发现，焊接时施加振动载荷时，焊道上的残余拉应力显着减小。在焊道附近的点处，残余应力为在远离焊道的点处，随着激励幅度的增加，残余应力趋向于拉伸。接下来，研究了通过所提出的方法减少残余应力的分析方法。残余应力的产生是由局部塑性变形引起的，因为初始残余应力很大，几乎等于屈服应力，因此，采用由质量和具有弹塑性特性的预紧弹簧组成的分析模型。减少残余应力率随着激励幅度的增加而增加，因此，可以通过实验和分析来证明该方法的有效性。