Magnesium alloy welding is a common and extremely complex welding skill, and it is difficult for ordinary people to master it. So what are the applications of magnesium alloy welding? And what is its solderability, please see the detailed introduction below!

Application of magnesium alloy welding in automobiles:

Magnesium is a lightweight silver-white metal. Adding appropriate proportions of aluminum, zinc, manganese and other metal elements to magnesium can generate a lightweight magnesium alloy material with high strength and stiffness, excellent casting and shock absorption. Magnesium alloys have been widely used in modern automobiles.

The advantages of magnesium alloy auto parts are:

① The mass is small, and the density is only 1.7 g/cm3 (the density of aluminum is 2.7 g/cm3, and the density of steel is 7.9 g/cm3). Replacing aluminum or steel parts with magnesium alloy parts will reduce the mass of the car a lot.

② The proportional strength of magnesium alloy is higher than that of aluminum alloy and steel, and the proportional stiffness is close to that of aluminum alloy and steel, which can accept a certain load.

③ Excellent castability and dimensional stability, easy processing, low scrap rate, and thus lower production costs.

④ Excellent damping coefficient, the shock absorption is greater than that of aluminum alloy and cast iron. The disadvantage of magnesium alloy is that the cost is still higher than that of aluminum alloy.

At present, magnesium alloy parts are mostly used in cars, commonly used in seat parts, instrument panels, steering column parts, steering wheels, brake and clutch pedal brackets, radiator frames, air conditioning equipment, sunroof equipment parts, mirror frames , Cylinder head cover, intake manifold, oil pump housing, auxiliary transmission bracket, junction box, motor housing, airbag seat and other components.

Weldability analysis of magnesium alloys:

1. The heat-affected zone and the weld bead are prone to coarse grains

Coarse grain is a shortcoming that magnesium alloy welding is prone to occur. Coarse grain will reduce the mechanical properties of magnesium alloy. The reason for the occurrence is that the overheating and cooling speed are fast. The solution is to choose appropriate welding specifications and refine the chemical composition of the electrode. Grain treatment, choose magnesium alloy electrodes containing manganese or iron.

2. Magnesium alloys are prone to oxidation and cracks

When magnesium alloys are welded, the main element that produces oxidative evaporation is magnesium. The oxidation of magnesium is more intense than that of aluminum, and the magnesium content is high, so only magnesium is oxidized. Magnesium oxide has a very high melting point and is solid in the molten pool. After cooling, it exists in the form of flakes in the weld. In addition, the magnesium alloy has coarse grains, and cracks are prone to occur after welding. During welding, the flow of argon gas should be appropriately increased, and the fluidity of the molten pool should be increased by stirring with the electrode to facilitate the emergence of magnesium oxide bubbles.

3. Generate bubbles

The reason for the bubble holes caused by magnesium welding is hydrogen, and the dissolution of hydrogen in magnesium is generally caused by the combination of magnesium and water. Therefore, the way to avoid the occurrence of pores during magnesium alloy welding is to minimize the water, dirt, etc. that enter the welding area.

4. Magnesium transpiration is easy to burn in the air

Because magnesium has a high oxidizing property, it is easy to burn in the air by transpiration. Magnesium alloys should be welded with argon tungsten arc welding, because the electrode does not melt and the maintenance of inert gas, the burning risk of magnesium is reduced.

5. Welding process of magnesium alloy

The melting temperature of magnesium alloys is low, only about 680 °C. The temperature at which melting begins is not much different from the temperature at which melting ends. Therefore, when welding and heating, it is necessary to continuously test the melting degree of the heating part with the electrode to avoid the occurrence of metal burn-through.

1) Clean the welding slag before welding. In order to avoid corrosion of magnesium alloys in the air, use stainless steel or copper wire brushes or scrapers to clean the welded parts.

2) Use manual tungsten argon arc welding, DC reverse connection, and right welding method of magnesium-manganese or magnesium-zirconium alloy electrodes.

3) Because of the very intense arc light and easy splashing during the welding of magnesium alloys, the operator must be careful to take safety precautions. There will also be a lot of magnesium oxide smoke and ozone during the welding process, so it is necessary to use high-power exhaust equipment.