Research On Casting Technology And Defects Of Casting Aluminum Alloy

Aluminum alloy castings are widely used in the industrial field, especially Al-Si alloys and Al-Cu alloys. Various defects of aluminum castings are unavoidable during production. Hot cracking defect often occurs in Al-Cu alloy castings because of its wide solidification range, while pinhole defect always appears in some Al-Si alloy castings because of their high silicon content leading to serious hydrogen absorption. In this paper, a couple of casting defects were researched such as cracking and misrun of ZL201 stent with thin-walled complex shape produced by sand casting; blow hole and cold shut of ZL102 casting with thin-walled complex shape produced by permanent mould casting; pinhole defects of ZL114 beam with thick-walled shape produced by sand casting. The characteristics of parts, alloy type, casting methods and defects have a strong representation.Analysis showed that, solidification characteristics of the alloy, non-uniform wall thickness of the components and structure volume of the sand cores result in hot cracking of the ZL201 stent, which can be solved by setting chills, using hollow structure in sand cores and poring under the low casting temperature710℃. High gas evolution, bad permeability of permanent mold and strong gas absorption of the alloy account for blow holes of the ZL102 casting, which can be solved by prolonging the heating time of the sand cores ; two flow of the alloy converging at thin section cause cold shut, which can be solved by modifying gating system; the poor quality of aluminum melt lead to pinhole defects of ZL114 beam, which can be solved by controlling the source of gas in liquid alloy, enhancing degassing technology of liquid aluminum, speeding up the casting solidification rate.