Measurements Of GMAW Arc Plasma Current Density And Temperature Field's Distribution

Arc diagnosis is of great significance to the establishment of the arc model and the improvement and development of melting gas welding.And the diagnosis of current density distribution and temperature field distribution are very important in arc diagnosis.In this paper,the current density distribution and temperature field distribution of GMAW arc are measured and calculated by improved split-cathode method and laser interferometry.The current density distribution of the GMAW arc exhibits a second order Gaussian distribution.The current density decreases with the center distance.The edge temperature is one tenth of the center temperature.The experiment also found that the value of the last point of the current density distribution is large,which is due to selecting a limited field of the arc.When the radius of the arc is determined to be infinite,the anomaly disappears.The GMAW arc holographic interferogram with different welding parameters was taken and the algorithm of inversion temperature field distribution using the interferogram was given.The temperature field distribution of the GMAW arc is also in the form of a second order Gaussian distribution.Its goodness of fit can attain 0.99 or more.As the center distance increases,the downward trend in the internal temperature of the arc plasma becomes soothing.The temperature field distribution is affected by welding current,wire extension,protective gas flow and droplet transfer stage.When the welding current rises,the arc radius increases,the center maximum temperature increases,and the edge minimum temperature increases.The temperature drop velocity and the area between the temperature-center distance curve and x-axis will also increase.Wire extension and air flow increase on the one hand will increase the temperature of the center,on the other hand it will decrease the edge temperature.Both of them make the temperature slow down with the center distance.The different droplet transfer stages also affect the arc temperature field distribution,which is mainly related to the establishment of the arc and the loss of heat when the droplet is removed.In these stages,the arc plasma will no longer satisfy the ionization equilibrium assumption and therefore can not be calculated.