Aluminum is a light metal with a specific gravity of 2.7 g / cm³. Melting temperature of aluminum is 660 degrees Celsius. The thermal conductivity of aluminum is large (3 times greater than that of low carbon steel).
Characteristics of aluminum and aluminum alloy welding
Aluminum is easily combined with oxygen to form an aluminum oxide (Al2O3) at a high melting point (2050 degrees Celsius) and a specific gravity greater than its own specific gravity (aluminum weight is 3.85g / cm³ ).
Phase transittion from solid to liquid aluminum state does not change color so that it is difficult to observe weld pool in arc welding
At high temperatures, liquid aluminum dissolve gas, especially H2, which is prone to causing cavitation.
At high temperatures, aluminum and aluminum alloys have very low durability, when temperatures are near the flowing temperature, the weld can be destroyed by its own weight.
Depends on the thickness of the workpiece that can be groove weld, bevel weld, non-bevel weld
Bend the edge when the workpiece is less than or equal to 1.5mm thick.
Bevelled when workpiece exceeds 4mm thick
Workpiece with a thickness of 5 - 15mm, bevel one side with an angle (70 ± 5) degrees.
Workpiece with thickness greater than 15mm, bevel on both sides.
Prepare the welding edge thoroughly clean the weld bead, the width of the cleaning (30 ÷ 35) mm
Detailed welding technique
Detailing must ensure that the surface smoothness between the components and the gap between the parts are uniform.
Corrugated welds must ensure a secure grip and ensure the spacing between bolts.
Distance between anchors and gap between two parts
The flame used for welding is neutral flame. If using excess fire oxygen will produce aluminum oxide as a susceptible to slag. If the acetylene flame is used, the weld will be easily smeared.
Select the flame to be soldered according to the thickness of the solder.
Flame capacity according to welding thickness:
Choice of welding rods:
Use a secondary welding rod to weld with the same composition as the welding metal components.
Common welding electrodes are:
Welding rod diameter:
Select rod diameter according to welding thickness:
Aluminum and aluminum alloys, for the exclusion of aluminum oxide and the prevention of oxidative melting of metals, use a separate solder for each type of welding material.
Pure welding of aluminum alloy is a mixture of chlorine and fluoride salts with the following composition:
27% NaCl + 50% KaCl + 14% LiCl + 8% NaF
Welded aluminum magnesium alloy welded drug components:
33.3% BaF2 + 24% MgF + 19% LiF + 14.8% KF + 2.8% MgO + 4.8% Na3AlF2
Depending on the thickness of the solder, it is possible to use left or right solder.
Welded joints of less than 5mm thickness should be welded.
Weld solder thickness of more than 5mm, should use the right welding method.
Tilt angle of the torch
At the beginning of welding, tilt angle of the torch should be large, then adjust the angle of inclination about (40 - 50) degrees.
Attention in aluminum and aluminum alloy welding techniques:
To improve the welding properties, after welding is done so lightly on the welding surface.
Care must be taken to clean the welded material so that the weld surface is not corroded.