Aluminum castings are prone to casting defects such as shrinkage cavities, bubbles, pores, and slag inclusions during the production process. How to repair defects such as pores in aluminum castings? If the use of electric welding, argon arc welding and other equipment for repair welding, due to the large amount of heat release, easy to produce thermal deformation and other side effects, can not 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 to repair the casting defects of aluminum alloy castings. Due to the small heat affected area of cold welding, it will not cause annealing deformation, cracks, hard spots and hardening of the base metal.

Pinhole is a common phenomenon encountered in aluminum casting. So what is the reason for this common phenomenon? In the aluminum casting process, the aluminum alloy will absorb a large amount of hydrogen during the melting and pouring process, and during the cooling process, due to the reduction of solubility, hydrogen will continue to be precipitated. Some data show that the solubility of more hydrogen in aluminum alloy increases with the increase of the temperature of the alloy solution, and decreases with the decrease of the temperature. When aluminum castinggeneratedWhen the solution changes from liquid to solid, the solubility of hydrogen in aluminum alloys decreases19 times.

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

Under normal production conditions, especially when casting thick aluminum alloys, pinholes are difficult to avoid. Generally speaking, for aluminum casting, if the crystallization temperature range is large, the possibility of mesh pinholes is much greater. This is because under normal casting production conditions, aluminum casting has a wide solidification temperature range, which makes aluminum alloys easy to form developed dendrites.

explained aboveIt isCommon defects of aluminum castings, hope to see the rightEverybodyIt helps.