Process methods for welding aluminium alloy materials for sale Haomei Aluminum

Today Haomei Aluminum will elaborate on the process methods for welding aluminium alloy materials for sale. There are generally 5 steps, which are detailedly explained below.

(1)Preparation before welding

The use of chemical or mechanical methods, strict cleaning of the weld bevel on both sides of the surface oxide film.

Chemical cleaning is the use of alkali or acid cleaning workpiece surface, the method can remove both oxide film, but also in addition to oil, the specific process is as follows: volume fraction of 6% ~ 10% of sodium hydroxide solution, at about 70 ℃ soak 0.5min → water washing → volume fraction of 15% of nitric acid at room temperature soak 1min for neutralization treatment → water washing → warm water washing → drying. The surface of the washed aluminium alloy is silvery white without lustre.

Mechanical cleaning can be used wind or electric milling cutter, but also scrapers, files and other tools, for the thin oxide film can also be used 0.25mm copper wire brush grinding to remove the oxide film.

Clean up immediately after welding, if placed for more than 4h, should be re-cleaned.

(2) Determine the assembly gap and positioning welding spacing

Welding process, the aluminum plate heat expansion, resulting in weld bevel gap reduction, welding before the assembly gap if left too small, the welding process will cause the bevels of the two plates overlap, increasing the unevenness and deformation of the welded plate; on the contrary, the assembly gap is too large, it is difficult to weld, and the possibility of burning through. Suitable positioning welding spacing can ensure the required positioning welding gap, therefore, choose the appropriate assembly gap and positioning welding spacing, is an effective measure to reduce deformation. According to experience, the more reasonable assembly process parameters for different plate thickness butt joints.

(3) Select welding equipment

At present, there are more types of welding products on the market, in general, it is appropriate to use AC tungsten arc welding (i.e. TIG welding). It is under the protection of argon gas, the use of tungsten electrode and the workpiece asked to produce the arc heat melting the base material and filler wire of a welding method. The welding machine works as the polarity of the AC current is changing periodically, with half the wave in each cycle being DC positive and half the wave being DC reverse. During the positive half-wave the tungsten electrode emits enough electrons without overheating, which helps to stabilise the arc. During the reverse half wave, the oxide film generated on the surface of the workpiece can be easily cleaned off to obtain a bright, beautiful and well formed weld.

(4) Choose welding wire

Generally choose 301 pure aluminium welding wire and 311 aluminium silicon welding wire.

(5) Selection of welding methods and parameters

Generally left welding method, welding torch and workpiece into 60 ° angle. Welding thickness of 15mm or more, to the right welding method, the torch and the workpiece into 90 ° angle.

When welding a wall thickness of 3mm or more, open a V-shaped bevel with an angle of 60° to 70°, with a gap of no more than 1mm, and finish with multi-layer welding. When the wall thickness is below 1.5mm, no bevel is opened, no gap is left and no filler wire is added. When welding fixed pipe butt joints, when the pipe diameter is 200mm and the wall thickness is 6mm, a tungsten electrode with a diameter of 3 to 4mm should be used, with a welding current of 220 to 240A and a filler wire with a diameter of 4mm, to finish with 1 to 2 layers of welding.