The Influence Of The Welding Residual Stress To TIG Under External Magnetic Field

Local rapid heating during the welding process resulting in uneven distribution of temperature field is the main factors of welding residual stress and welding residual stress welding cracks, fatigue fracture, brittle fracture, stress corrosion cracks and other damage in the form of the main factors, therefore welding residual stress the distribution and size of the welded structure of the welding quality, dimensional accuracy, security, performance and service life also has a direct or indirect influence. Therefore, deepening study of welding residual stress to improve the quality of welding has a very important significance.In this paper, plus a DC longitudinal magnetic field in the TIG welding arc, changing the size of the magnetic field strength, making the welding arc charged particles by the Lorentz force to accelerate the arc of rotation to edge aggregation, and thus expansion the arc, reduces the coefficient of the heat source of the arc column center to avoid a concentration of energy to accelerate the molten pool of metal convection, reducing the molten pool welding temperature field gradient to achieve a reduction of welding residual stress. While in the process test, based on ANSYS software, the external applied magnetic field TIG welding temperature field and stress field simulation study magnetic field on the TIG welding residual stress.In this article, according to the external magnetic field TIG welding characteristics, the motion model of the external DC longitudinal magnetic field TIG welding heat source, thermal elastic-plastic finite element theory, the life and death cell technology, whether the magnetic field of TIG welding Q235steel welding process temperature and stress field a numerical simulation, and wait until the contours of the temperature field and stress simulation results and analysis of the reasons for the welding temperature gradient in the magnetic field decreases and residual stress peak reduced. At the same time, changing the magnetic field strength, TIG welding the Q235steel and LF21aluminum alloy specimens, use blind hole method measured the weld residual stress values, combined with the weld width and weld shape analyzed the external magnetic field acting on the mechanism of TIG welding and the residual stress is reduced reasons.The results show that external dc longitudinal magnetic field TIG welding arc expansion, the arc heat source coefficient is smaller, increasing the weld width, and reduces the peak temperature and the temperature gradient, reducing the welding residual stress values. At the0.5A of extra excitation current, the residual stress decreases with increasing magnetic field strength, the weld shape is also better. Process test results and the simulation are consistent to prove that the magnetic field can effectively reduce the TIG welding residual stress, and opened up new method for the welding residual stress and deformation studies.