Experimental Study On The Influence Of Groove Space Constraints On The Plasma Characteristics Of Titanium Alloy Laser-MIG Hybrid Welding

The welding technology of titanium alloy thick plate is a difficult point when manufacturing thick wall components of large equipment.Laser arc composite welding is a common process in welding thick plates.When welding thick plates,the process of welding thick plates needs to be realized through the way of opening the groove and multi-layer and multi pass welding.The depth of the slope has an important effect on the effect of laser arc compound welding,but the law needs to be studied in depth.Through the design of special step shaped specimen,the step depth changes gradually according to the equal difference mode.Each time the 2mm is changed,a variety of welding with different groove depth is realized on a welding plate.The spectral information of the 3mm position on the center line of the slope and above the bottom of the bevel is collected by spectrometers,and the spectral information of the plasma is represented,and the morphology and droplet transition of the composite plasma are taken with the high-speed camera along the weld direction.The influence of groove depth on laser-MIG hybrid welding is analyzed and explored.The specific experimental conclusions are as follows:?1?With the increase of groove confinement space,the temperature of the plasma tends to decrease linearly.When the plasma is not restrained,the plasma temperature is the largest,10589K.When the groove depth is 20mm,the minimum temperature is 8587K.The reason is:when the confinement space is increased,the velocity of metal vapor is slowed down from the slope,and the temperature of the metal vapor is lower than the plasma temperature.The deeper the groove is,the lower the temperature of the plasma is measured.In addition,the slower the groove confinement space is,the slower the drop drop and the temperature of the droplet are relative to the plasma.It is also lower,so the reason will also result in the increase of the confinement space and the decrease of the plasma temperature.?2?With the increase of groove confinement space,the density of electrons increases approximately linearly.When the plasma is not restrained,the electron density is 1.23×10¹66 cm^-3;when the groove depth is 20mm,the electron density is 1.43×10¹66 cm^-3.The reason is that the larger the confinement space is,the more metal vapor exists in the interior of the groove,and the metal vapour is easily ionized out of the free electrons,so the larger the confinement space is,the greater the electron density is.?3?With the increase of groove confinement space,the area of plasma tends to decrease linearly.When the plasma is not restrained,the area is the largest,25.66mm²;when the groove depth is 20mm,the plasma area is the smallest,7.10mm².The reason is that,when the confinement space is increased,the velocity of the gas is blown to the plasma by the influence of the geometric relationship of the slope,and the more obvious the compression effect of the protective gas is on the plasma.Therefore,when the confinement space of the groove increases,the area of the plasma gradually decreases.?4?With the increase of groove confinement space,the transition period of droplet is approximately linear upward trend.When the plasma is not restrained,the transition period of droplet is 70ms.When the groove depth is 20mm,the transition period of droplet is 121ms.The reason is that the deeper the slope is,the greater the reaction force of the metal vapor is,the more obvious the hindrance effect on the droplet transition,which leads to the increase of the transition period of the droplet when the groove's confinement space is increased.?5?As the groove depth increases from 0 to 20mm,the weld width decreases from6.7mm to 4.5mm,and the penetration increases from 2mm to 3.2mm.The reason is that the width of the arc spreading gradually decreases with the increase of the confinement space of the slope,so the melting width decreases gradually;the total energy input is certain,the smaller the plasma profile,the more concentrated the energy is,so the melting depth gradually decreases with the increase of the confinement space and the melting depth gradually increases.