| Aiming at solving the disadvantages such as grain coarsening in Heat AffectedZone (HAZ) when Submerged Arc Welding (SAW) is applied to thick plate with highheat input and the bad bead shape due to higher welding speed, this paper put forwarda new pulsed current/voltage SAW technology on the basis of the development trendsof SAW domestic and international.This paper presented the brief principle of the MCU-cored pulse controller.Numbers of experiments were designed and finished with the help of orthogonalmeans.This paper studied the effects of pulse parameters (background current, peakpulse current, frequency and duty cycle) on the welds shaping when using sharp-falloutput characteristics power source and varying-speed wire feeder. The results of theexperiments shows that pulsed Submerged Arc Welding can control the weld shapeeffectively by changing the pulse parameters, and this technology can receive lessergrain size, and for appropriate frequency range (For the system presented above, it'sabout 25Hz), greater penetration depth can be got using this technology comparingwith the ordinary SAW when using equal heat input.For the purpose of solving the problem of bad bead shape (mostly be undercut)when SAW is used in high-speed welding, the technology of Pulsed voltageSubmerged Arc Welding with flat output characteristic power source and constantspeed wire feeder is put forward, this system sends out pulsed voltage. This paperanalysed the cause of undercut, the basic theroy for solving weld undercut was brieflypresented. This technology was firstly used in the water-cooling panel welding inShanghai Boiler Works Co. Ltd. This technology can solve the problem of undercutwhen the system is used to weld thin flat steel-steel tube as the welding speed ishigher by 20-45%, when to weld thick flat steel-steel tube, it can receive good beadshape even when the welding speed is higher by 20-45% than the ordinary techniqueswithout any slope prepared. The technique received great success.
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