Study Of TIG Welding Process Under The Effect Of Environmental Stress

Due to the needs for the exploration of offshore oil and gas, the world sees an annual increase in projects involving the construction or repair of submarine pipelines. As a result, much emphasis has been put to researches on methods concerning the welding and repair of submarine pipelines, among which hyperbaric TIG welding is a common one. In order to optimize the procedure and improve the efficiency hyperbaric TIG welding, it is of great significance to study the welding arc of it considering the external pressure that increases with depth.The author intended to collect parameters of TIG welding in high pressure by utilizing high-speed camera and a system acquiring arc spectrum. And conducting TIG welding under a pressure of0.1～0.5Mpa, the author managed to gather related arc images as well as information on arc spectra.After reviewing former researches on the simulation of TIG welding, the author established a new model of TIG welding and simulated and compared the temperature fields of TIG welding under normal and high pressure using software of fluid simulation, FLUENT, respectively. It’s shown that the temperature of TIG welding arc in high pressure varies less than that of TIG welding arc under normal pressure with a distinct decrease in the highest. What’s more, the temperature near the anode zone is higher than that of TIG welding arc under normal pressure. The author also studied the impact of external pressure on the appearance of welding arc based on images taken by high-speed camera. Evidence shows that a higher pressure can lead to the constriction of TIG welding arc and also a great weld width and weld penetration when comparing different pieces of work of TIG welding under various pressures. Last but not least, the author calculated the temperature of arc under various pressures through Boltzmann based on the collected spectra and found that the temperature of TIG welding arc holds a negative correlation with external pressure.This paper, combining simulation and real experiments, studied the impacts of external pressure on the appearance and temperature field of TIG welding arc, exploring the physical characteristics of TIG welding arc under high pressure and providing some theoretical basis for the optimization of TIG welding procedure.