The main feature of pulse TIG welding is to use controllable pulse current to heat the workpiece. When each pulse current passes through, the work is heated and melted to form a molten pool. When the base current passes through, the molten pool condenses and crystallizes and maintains arc combustion. Therefore, the welding process is an intermittent heating process, and the weld is superimposed by one molten pool. Moreover, the arc is pulsating, alternating by large and bright pulsed arc and small and dark dimensional arc cycle, and the arc has obvious flicker phenomenon.
Pulse TIG welding can be divided into:
DC pulse TIG welding
AC pulse TIG welding.
According to the frequency, it can be divided into:
1) Low frequency 0.1 ~ 10Hz
2) If 10 ~ 10000hz;
3) High frequency 10 ~ 20kHz.
DC pulse TIG welding and AC pulse TIG welding are suitable for the same welding materials as ordinary TIG welding.
Medium frequency TIG welding is rarely used in practical production because the noise pollution caused by arc is too strong for people’s hearing. Low frequency and high frequency TIG welding are usually used.
Pulse TIG welding has the following advantages:
1) The welding process is intermittent heating, the high temperature residence time of molten pool metal is short, and the metal condenses quickly, which can reduce the tendency of cracks in heat sensitive materials; The butt weldment has less heat input, concentrated arc energy and high stiffness, which is conducive to the welding of thin plate and ultra-thin plate, and the joint has little thermal impact; Pulse TIG welding can accurately control the heat input and weld pool size to obtain uniform penetration, so it is suitable for single-sided welding, double-sided forming and all position welding. After the pulse current frequency exceeds 10kHz, the arc has strong electromagnetic shrinkage, the arc becomes thinner and has strong directivity. Therefore, high-speed welding can be carried out, and the welding speed can reach 30m / min;
4) The high-frequency oscillation of pulsed TIG welding is conducive to obtain the full-phase microstructure of fine grains, eliminate pores and improve the mechanical properties of the joint
Post time: Sep-26-2021