Welding process of automotive aluminum radiator

The application of aluminum alloys in automobiles is the development direction of automotive materials. At present, due to the use of aluminum alloy instead of steel, the weight of the car has been reduced by 20% -50%, and fuel has been saved by more than 10%. And all aluminum cars not only reduce weight, but also improve corrosion resistance, thereby extending the service life of the materials. The aluminum structure connections on automobiles require welding, and the welds must have good mechanical properties and no air holes.

In addition to structural components, the radiator in cars is also developing towards aluminum alloying. Traditional car radiators use copper alloy, which is heavy and costly. After the improvement of welding technology for aluminum alloys, aluminum alloy radiators have more advantages than copper alloys.

Standardized welding processes are a prerequisite for high quality,

The welding difficulties of aluminum alloy radiators include:

Welding crack tendency and welding deformation. Welding deformation control is not good, but it affects the appearance of the product, and even affects the installation and use of the product. Therefore, welding deformation should be strictly controlled.

1. Welding method: Either brazing or fusion welding can be used.

In order to improve work efficiency and reduce the cleaning process after welding, manufacturers will use TIG welding and MIG welding.

2. Selection of welding materials:

Welding material is an important factor affecting welding quality. Therefore, when selecting aluminum welding wire, it is necessary to consider its tendency towards factors such as porosity and cracks, as well as the strength, thermal conductivity, and fluidity of the weld metal.

Radiator manufacturers usually choose 4043 aluminum silicon welding wire with low melting point and good crack resistance as the filling material; Most tungsten electrodes use cerium tungsten electrodes with stable welding arcs; The protective gas is argon with a purity of ≥ 99.99%.

When analyzing the welding materials of aluminum alloy radiators, we found that even the base material with high magnesium content did not choose aluminum magnesium welding wires because magnesium can reduce the thermal conductivity of the weld seam and easily cause precipitation hardening during the welding process.

Therefore, we usually use aluminum silicon welding wire as the filler metal, which is not affected by precipitation hardening heat treatment. Its fluidity increases with the increase of silicon content, reducing the tendency for hot cracking. Compared with aluminum magnesium welding wire, it improves the thermal conductivity of the weld seam.

3. Welding tools:

In order to improve work efficiency, manufacturers usually make simple welding specialized fixtures for clamping workpieces, and assemble and fix the heat sink. The clamping force of the fixture can be freely adjusted to ensure uniform clamping force on the workpiece.

4. Cleaning before welding:

In order to avoid the occurrence of welding cracks, it is required to use physical or chemical methods to clean the welding area before welding, especially for the oxide layer that cannot be effectively "broken" by "cathode atomization", which must be thoroughly removed.

5. Post weld treatment:

To improve the corrosion resistance, thermal conductivity, and decorative properties of the radiator, the overall surface of the radiator will be sprayed after welding to ensure that all technical indicators meet the design requirements.

6. Weld quality inspection, qualified welds should have:

Tensile test: All fracture surfaces of welded specimens are on the base metal, and the mechanical properties of the weld seam meet the design requirements.

Pressure test: The specimen is deformed, but the weld seam is still intact.

Air pressure test: The weld seam has no leakage and complies with national standards.