Aluminium and aluminium alloy solder the doubt in the process and processing method

Because aluminium and aluminium alloy have distinctive physical function and chemical function, soldering so the meeting in the process happens a series of doubt, detailed for, basically have the following:
One, strong oxidisability
The affinity of aluminium and oxygen is very strong, close and hale AL2O3 alumina film is made extremely easily in air in metallic appearance with oxygen connection, ply is about 0. 1 μ M, melting point is as high as 2050 ℃ . Alumina film is soldering the crackajack connection that the metal can prevent in the process, form slag inclusion. Oxidation film returns can adsorptive moisture content, cause the welding line when soldering to make air hole. These defect, can drop solder the function of contact. Solder to assure quality, be necessary before solder severity clears the oxide of weldment appearance, avoid to soldering oxidize once more in the process, undertake useful maintenance to fused metal and the metal that are in high temperature to fall, this is a when aluminium and aluminium alloy solder important measure. Detailed maintenance method is:
1, workpiece groove is eradicated to reach with machinery or chemical method before solder all round part and the oxide with outside welding wire;
2, solder those who choose qualification want to safeguard gas to undertake maintenance in the process;
3, when gas welding, choose flux, soldering the oxidation film that broken bath appearance raises with welding wire ceaselessly in the process.
2, aluminous thermal conductance and specific heat are big, heat conduction is fast
Although the melting point of aluminium and aluminium alloy is inferior, but coefficient of thermal conductivity, specific heat capacity is very large, soldering the heat energy with a lot of mediumer process is conducted quickly base metal is in-house, to acquire high quality solder contact, be necessary to choose the heat source with energy concentration, great power, need to choose the technical way such as warm-up sometimes, ability completes fusion welding process.
3, linear expansion coefficient is big
The linear expansion coefficient of aluminium and aluminium alloy is 2 times of steel about, the bulk when condensing shortens rate amount to 6. 5% - 6. 6% , consequently easy happening solder be out of shape. Avoid metabolic useful idea is besides choose sound technology parameter and solder outside order, choosing suitable welder to install also is very important, solder when thin plate especially such. Other, when certain aluminium and aluminium alloy solder, the tendentiousness that forms crystallization crackle in welding line metal and the tendentiousness that form liquefacient crackle in hot influence area all bigger, it is because of too great internal stress normally inside brittleness temperature interval produce hot crack. This is aluminium alloy, especially one of the commonnest severe weakness when excel in aluminium alloy solders. Soldering actually the measure that this kind of flaw avoids in the spot basically is to improve contact to plan, choose to solder reasonably technical parameter and solder order, choose those who be used to characteristic of mother capable person to solder stuff stuff.

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