Study On The Plasma In The Laser-pulse GMAW Hybrid Welding Based On Spectrum Diagnosis

With lots of advantages such as good welding gap bridgingcapability, big welding penetration, high welding efficiency and processstability, small welding deformation and wide scope of weldablematerials, laser-pulse GMAW hybrid welding becomes one of the mostimportant welding method. The study on physics parameters such astemperature,electron density and shape of the plasma in the welding, ishelpful to propose the optimization scheme of hybrid welding, providingtheory support and guidance for the production of special hybrid weldingpower source. It is also helpful to guide people to precisely control thestability of welding process, welding efficiency and quality. In the paper,plasma shape, distribution of spectral line, temperature and electrondensity is studied by spectrum diagnosis and high-speed photography.This paper studied the effect of the interaction between laser andGMAW on the plasma shape, spectral line profile, and then measuredtemperature and electron density of the plasma by using Boltzmann spectrometry and the Stark width of spectrum. The study found that laserattracts arc in hybird welding. Arc expanded after absorbing energy oflaser energy and the length of arc got long. Laser changed the distributionof temperature and electron density in pulse GMAW welding and madetemperature and electron density of arc plasma decreased. Thetemperature and electron density of laser area is far higher than that of arcarea in Laser-pulse GMAW hybrid welding.Secondly, this paper studied the effects of different processparameters in hybrid welding.The study found that the change of processparameters had no obvious effect on temperature and electron density oflaser area, but a great influence on temperature and electron density of arcarea. When arc is leadeading, there is an obvious transition area with lowplasma temperature and electron density between the two heat sources.With the increase of heat source separation distance, temperatures of arcplasma decrease, and electron densities of arc plasma first increase andthen decrease. With the increase of He content or arc voltage, thetemperatures and electron densities of arc plasma also increase. With theincrease of laser power, the temperatures of arc plasma have not changedsignificantly, but the electron densities increase.