Method for reducing laser welding pores of cast magnesium alloy
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A technology for casting magnesium alloys and laser welding, applied in laser welding equipment, welding equipment, welding/welding/cutting items, etc., can solve the problem of limited preventive measures
Inactive Publication Date: 2009-08-12
BEIJING UNIV OF TECH
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Problems solved by technology
At present, the measures to prevent pores in laser welding of cast magnesium alloys are very limited. Traditional technological measures such as: strengthening protection, creating conditions conducive to gas escape, and cleaning before welding are harmful to cast magnesium alloys with very high original hydrogen content inside the base metal. doesn't work
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Embodiment 1
[0019] In the experiment, for cast magnesium alloys with base metal shrinkage porosity of 2% to 5%, the thickness of the plate is 4mm. During self-fluxing welding, the process parameters are optimized. The power is 3500W, the welding speed is 3m / min, and the defocus is In the case of -2, penetration can be achieved, and the obtained weld section is as follows figure 2 shown.
[0020] In the case of adding welding wire, the power is 3500W, the welding speed is 3m / min, the defocus is -2, the wire feeding speed is 1.0m / min, h=0.5mm d=0.5mm a=35° The weld cross-section is as image 3 shown.
Embodiment 2
[0022] In the experiment, for the cast magnesium alloy with base metal shrinkage rate of 12-15%, the thickness of the plate is 4mm. During self-fluxing welding, the process parameters are optimized. The power is 3500W, the welding speed is 2m / min, and the defocus amount is - In the case of 2, penetration can be achieved, and the obtained weld cross section is as follows Figure 4 shown.
[0023] In the case of adding welding wire, the power is 3500W, the welding speed is 2m / min, the defocus is -2, the wire feeding speed is 1.8m / min, h=0.5mm d=0.5mm a=35° The weld cross-section is as Figure 5 shown.
[0024] It can be clearly seen from the figure that the effect of filler wire on the porosity control of laser-welded cast magnesium alloys is obvious. For cast magnesium alloys with shrinkage porosity of 2% to 5%, the average porosity of the weld is 5% in the case of self-fluxing welding. The average porosity of the weld after welding wire is 0.5%.
[0025] The average porosi...
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Abstract
The invention relates to a method for reducing casting magnesium alloy laser welding porosity which belongs to the technical field of high-power laser processing, in particular to laser welding of casting magnesium alloy. The method is characterized in that the laser power P and the defocusing amount are firstly adjusted to ensure the sufficient weld penetration and weld width. Then the welding wire can be melted down stably before filled in a weld puddle through adjusting the distance d and the height h between a welding wire and a spot and the angle a formed by the welding wire and a workpiece; the wire feed speed V1 and the welding speed V2 are then adjusted to ensure the entry of appropriate amount of welding wire into the weld puddle. In addition, the porosity is further reduced through adjusting the clearance D between two plates. During the welding process, the protective atmosphere with Ar gas in the inner layer and He gas in the outer layer is provided by a nozzle. For metals with the base metal of great shrinkage porosity rate such as magnesium alloy, the purpose of adding the welding wire is essentially to improve the uniformity of the seam structure configuration, 'dilute' the over saturated hydrogen and reduce the porosity of the seam structure.
Description
Technical field: [0001] The invention belongs to the technical field of high-power laser processing, in particular to laser welding of cast magnesium alloys. Background technique: [0002] Magnesium alloys have broad application prospects in the fields of automobiles, motorcycles, weapons, aerospace, and computer electronics industries due to their light weight, high specific strength, good recycling performance, no pollution, and rich resources. Magnesium alloys It is mainly divided into two categories: wrought magnesium alloy and cast magnesium alloy. At present, more than 90% of magnesium alloy products are cast. These structures are often manufactured by welding processes. Since the 1960s, tungsten argon arc welding (TIG welding), electron beam welding, friction stir welding, and resistance electric welding have often been used. Since the 1990s, the laser welding process has been adopted. The most important problem in the welding process is the pores. The relevant res...
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