Classification of internal casting defects of piston

Casting defectCauseImprovement measures
Unqualified chemical compositionThe composition of master alloy ingot is unqualified, and the burden of electric furnace smelting is not allowedSelection of master alloy ingot ingredients
Macro dispersed pores and slag inclusion > grade 4Insufficient degassing, static and slag raking of electric furnace; Unqualified aluminum water is scooped during pouring; Low temperature of molten aluminumDegassing shall be carried out carefully to ensure that the slag is removed during the static time before pouring; Increase the temperature of molten aluminum;
Macro concentrated pores and slag inclusion > grade 4Insufficient degassing, static and slag raking of electric furnace; Unqualified aluminum water is scooped during pouring; When the temperature of molten aluminum is low, scoop the molten aluminum into it;Pay attention to pushing slag and scooping aluminum water;
Unqualified metallographic structure > grade 5Insufficient degassing, static and slag raking of electric furnace; Unqualified aluminum water is scooped during pouring; Low temperature of molten aluminum,Degassing shall be carried out carefully to ensure that the slag is removed during the static time before pouring; Increase the temperature of molten aluminum;
Hardness less than HB100Poor heat conduction of external mold and heat transfer of baseImprove the heat conduction of the external mold and reduce the water temperature
Insufficient tensile strengthZL108 has poor deterioration effect, poor heat conduction of external mold and hot baseScrap the outer mold and reduce the water temperature
Ring groove shrinkage and loosenessThermal conductivity difference of external mold, mold ° C > core ° CImprove the heat conduction of the outer mold and increase the temperature of the core mold by ° C
Slag inclusion hole in pin holePin hole core die is too cold; Or assembly with water vaporThermal insulation of pin hole core mold stained with stone ink
Slag inclusion air hole at wall and stop endInsufficient degassing, static and slag raking of electric furnace; Unqualified aluminum water is scooped during pouring; Low temperature of molten aluminumDegassing shall be carried out carefully to ensure that the slag is removed during the static time before pouring; Increase the temperature of molten aluminum;
Pin hole crackCore pulling die is too early, and the core die is deformed;Postpone the core pulling die and pay attention to the mode of core pulling. The core die is deformed and seriously scrapped.
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