Aluminum alloy castings are prone to casting defects such as shrinkage cavities, sand holes, pores, and slag inclusions in the production process. How to repair the pores and other defects of aluminum alloy castings? If electric welding, argon arc welding and other equipment are used for repair, it is easy to produce thermal deformation and other side effects due to the large amount of heat release, which cannot meet the requirements of repair welding. The cold welding repair machine is based on the principle of high-frequency electric spark instantaneous discharge and non-thermal surfacing. It is used to repair the casting defects of aluminum alloy castings. Due to the small heat affected zone of cold welding, it will not cause annealing deformation, cracks, hard spots and hardening, after melting, the repair material and the base material can be solidified at the same time. This combination is firm, can be ground, milled, and filed, and is dense and will not fall off. The cold welding repair machine is to repair small defects such as pores and sand holes in aluminum alloy castings. Ideal method.

Pinhole is a common phenomenon encountered in aluminum alloy foundries when casting aluminum alloys, so what is the cause of this common phenomenon?? In the process of aluminum casting, aluminum alloy will absorb a large amount of hydrogen in the process of melting and pouring, and in the process of cooling, hydrogen will continue to precipitate due to the decrease of solubility. Data show that the solubility of more hydrogen in aluminum alloy increases with the increase of solid solution temperature of the alloy, and decreases with the decrease of temperature. When the solution changes from liquid to solid, the solubility of hydrogen in aluminum alloy decreases by 19 times.

Therefore, in the process of liquid cooling and solidification of aluminum alloy, at a certain moment, the hydrogen content exceeds its solubility and precipitates in the form of bubbles. The hydrogen bubbles formed by hydrogen supersaturation will form fine and scattered pores in the solidification process and then float up and discharge, that is, it is difficult to avoid pinholes under normal production conditions, especially thick sand castings. Aluminum alloy is melted and poured in an environment with high relative humidity, pinholes in castings are particularly serious, which is why it is often suspected that pinhole defects in aluminum alloy castings are less in the dry season than in the rainy and rainy seasons.

Under normal production conditions, especially when casting thick aluminum alloy, it is difficult to avoid pinholes. Aluminum alloy is melted and poured in an environment with high relative humidity, and pinholes in castings are particularly serious. This is why it is often suspected that pinhole defects in aluminum alloy castings are less in dry season than in rainy season and rainy season. Generally speaking, for aluminum alloy, if the crystallization temperature range is wider, the possibility of mesh pinholes is much greater, this is because under normal casting production conditions, cast aluminum parts solidification temperature range is wide, so that aluminum alloy is easy to form developed dendrites.

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