磁场作用下电弧行为及其作用下焊接接头微观组织和性能研究

发布时间：2018-05-24 05:46

  本文选题：横向偏转磁场 + 横向旋转磁场　； 参考：《上海工程技术大学》2016年硕士论文

【摘要】：对焊接过程施加磁场,一方面可以改变焊接电弧的形态,进而改变焊接电弧的作用区域以及能量的分布,另一方面还可以对熔池金属进行搅拌,抑制枝状晶的形成,最终起到细化晶粒的目的,改善焊缝的质量。本文主要研究了在横向偏转磁场和横向旋转磁场作用下电弧的运动形态,重点研究在横向偏转磁场和横向旋转磁场作用下,不同的磁场大小对于电弧的偏转幅度和电弧形态。研究表明,施加直流横向偏转磁场时,电弧偏转幅度会随着磁场强度的增大而增大,电弧在母材作用范围在偏转一侧被拉长,形状呈近半圆加椭圆,并且电弧的稳定性也逐渐变差。施加交流横向偏转磁场时,在一定磁场范围内,电弧发生摆动的最大偏转幅度会随着磁场强度增大而增大,电弧在母材上作用范围在偏转方向两侧拉长,形状呈被拉长的椭圆。当磁场频率600≤υ≤900时,电弧会以焊接方向轴线为中心,左右摆动;当磁场的频率900≤υ≤1500时,电弧会受到一个“磁约束力”的作用,宏观观察电弧的偏转和旋转并不明显,此时的的焊接电弧会相对稳定;当磁场频率1500≤υ时,此时带电粒子受洛伦兹力增大,此时电弧不太稳定,并且电弧的亮度下降,并有熄弧的倾向。施加横向旋转磁场时,电弧发生旋转,磁场强度较小时,电弧在母材上作用区域呈两个同心圆,内部小圆部分热量较大;当磁场强度到某一特定值时,电弧作用范围形状为近似圆形,面积较未施加磁场时变大,能量较小;磁场强度进一步增大,母材受热区域为圆环状,此时不能形成焊缝。当改变磁场的频率后,电弧稳定性的变化与横向交流磁场中电弧随着磁场频率变化类似。文章进行了工艺试验,并对所取得的焊接接头进行了机械性能研究和微观组织的观察。试验表明旋转磁场的施加会改善焊缝成形,使得熔池变浅变宽,改善焊缝中部突出的现象,一定程度上降低焊缝的应力集中。横向旋转磁场的施加会细化焊缝金属和HAZ金属的晶粒,减少板条马氏体和块状铁素体的含量和晶粒尺寸,同时也会细化针状铁素体,使得焊接接头的性能提高。施加焊接磁场后的焊接接头在硬度方面会有一个明显的提高,同时缺陷也会减少。
[Abstract]:On the one hand, applying magnetic field to welding process can change the shape of welding arc, and then change the area of action and the distribution of energy of welding arc, on the other hand, it can stir the molten pool metal and inhibit the formation of dendrite. Finally, the aim of grain refinement is to improve the quality of weld seam. In this paper, the motion of arc under the action of transverse deflection magnetic field and transverse rotating magnetic field is mainly studied, and the effect of different magnetic field on the arc deflection amplitude and arc shape is mainly studied under the action of transverse deflection magnetic field and transverse rotating magnetic field. The results show that when the DC transverse deflection magnetic field is applied, the arc deflection amplitude will increase with the increase of the magnetic field intensity, the arc will be elongated on the deflection side of the base metal, and the shape of the arc will be nearly semicircle and ellipse. And the stability of the arc is becoming worse. When the AC transverse deflection magnetic field is applied, in a certain magnetic field range, the maximum deflection amplitude of the arc swinging will increase with the increase of the magnetic field intensity, and the arc action range on the base metal will be elongated on both sides of the deflection direction with the shape of the elongated ellipse. When the frequency of magnetic field is 600 鈮，

本文编号：1927906