外加直流磁场下微束等离子电弧行为与焊缝成形研究

Micro plasma arc behavior and weld formation under applied DC magnetic field

为实现薄壁件金属在增材制造中成形及成性的精确控制,基于带电粒子在直流磁场作用下的运动规律,研究了外加直流磁场作用下电弧行为,得到电弧偏转程度、偏转方向与外加磁场之间的关系.在电弧偏转的基础上分析了焊缝形貌、焊缝晶粒变化原因.结果表明:外加直流磁场作用下电弧发生偏转,在试验参数范围内随磁场强度增加,电弧偏转程度增大,且电弧偏转方向与外加磁场方向相关;外加正向直流磁场时熔池向焊接方向后方偏移,焊缝余高相对增加,焊缝晶粒较无外加磁场细化;外加反向直流磁场时熔池位于电弧下方,焊缝余高相对降低,焊缝晶粒较外加正向磁场更加细化.外加正向直流磁场控制焊缝形貌,具有“控形”效果;外加反向直流磁场有明显的细化晶粒作用,可以达到“控性”目的.

In order to realize the precise control of forming and quality of thin-wall part metal in additive manufacturing,based on the motion law of charged particles under DC magnetic field,the arc behavior under DC magnetic field was studied,and the relationship between the deflection degree,the deflection direction of the arc,and the applied magnetic field was obtained.On the basis of the deflection of the arc,the causes of the changes of weld appearance and weld microstructure were analyzed.Results show that the arc was deflected by the applied DC magnetic field,the deflection of the arc increased with the increase of the magnetic field strength within the range of the test parameters,and the deflection direction of the arc was related to the direction of the applied magnetic field.With the applied forward DC magnetic field,the molten pool was offset to the rear of the welding direction,the reinforcement was increased,and the weld microstructure was thinner than that with no external magnetic field.When the reverse DC magnetic field was applied,the molten pool was located under the arc,the reinforcement was relatively lower,and the weld bead structure was more refined than the external forward magnetic field.The applied forward DC magnetic field controlled the shape of the weld and the applied reverse DC magnetic field had a significant effect on the grain refinement.