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CMT (Cold Metal Transfer) cold metal transfer technology as a kind of MIG / MAG welding with low heat input welding speed, stable arc, little spatter, weld quality, high precision is repeated, but because of the low heat input , melting depth, currently available only for high-speed welding of sheet. Laser - arc hybrid welding is an emerging specialty laser processing technology, it two physical nature, the energy transfer mechanism distinct laser and arc heat source composite together simultaneously on the same machining position, give full play to the two heat sources their respective strengths, but also with each other to make up for their shortcomings, to form a new and efficient heat source. In conclusion, the laser at home and abroad - research status on the basis of the arc hybrid welding, laser-CMT arc hybrid welding equipment developed by means of Harbin Welding Institute, 18-8 stainless steel as test material, the first study of the Nd: YAG laser CMT The composite heat of the welding process as well as the Nd: YAG laser CMT composite arc characteristics of the heat source and the molten pool morphology. The study showed that: ND: YAG laser CMT composite heat CMT compared, it is possible to more stable arc, to improve the weld shape. Laser arc burning the particles of the charged particles and the low ionization potential, and also increases the temperature difference with the surrounding environment so that the arc center, both the arc the path resistance becomes low, thereby to maintain the arc combustion The voltage is reduced, so that the composite heat source can be a more stable arc, to improve the weld. Improve the weld pool morphology, reduced spatter. To the laser, the laser weld pool with CMT molten pool coupled together, increase the forefront of the distance of the wire point of the molten pool, increasing the oscillation of the molten pool forefront of base metal melt drops off in the bath, shock cause the molten bath to reach the molten bath forefront preform energy is weakened, when the collision energy becomes small, and the bath forefront spatter reduction. Increased weld penetration. 304 stainless steel welding, the laser power PL = 2kW, from the amount of coke △ z = 3mm, welding current I = 150A, low-speed welding composite weld depth increased CMT welding 4 times, 9 times can be achieved when the high-speed welding. To improve the welding speed. High-speed welding plasma concentration is not enough can not sustain the arc between the electrode and the weldment stable combustion, the laser improves the weldment surface plasma concentration, play a stable arc to arc. Increase the degree of cross-weld offset. Under the experimental conditions, CMT arc power is always less than 2 kW laser energy, laser energy / arc energy ≥ 1:1, laser added to make the composite molten pool temperature is significantly higher than the CMT, the surface tension of the molten pool is far less than CMT, good fluidity in CMT, thus increasing the the cross welds offset. Nd: YAG laser CMT composite heat source application to thick horizontal welding to achieve in pure argon gas protection, you can get a stable arc and good weld, to avoid the multi-layer multi-pass welding \unfused interlayer defects generated.
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