Patent ID: 6261390
Filing Date: 2001-07-17
Classification: C22C,C22F,F02F,F05C

Abstract:
A method for nodulizing the silicon in Al-Si alloy castings having a silicon (Si) content in the range of 8.0-23.0%, which comprises the steps of:a) heating a selected start Al-Si alloy mass to its alloy liquidus temperature, producing a melt;b) adding a master alloy mixture into the melt at a master alloy temperature of 150 deg. C above the start alloy liquidus temperature, said master alloy mixture comprising: Al-Ti 1-10% weight titanium and 90-99% weight aluminum; Al-B 0.2-3.0% weight boron and balance aluminum; Al-RE 4.0-10% weight rare earth elements and 90-96.0% weight aluminum; AI-Zr 1.0-5.0% weight zirconium and the balance aluminum; and Cu-P 5.0-8.0% weight phosphorous and 92.0-95.0% weight copper; stirring the master alloy mixture in the melt and holding for a short time period;c) degassing the melt with nitrogen and forming a treated molten mass;d) pouring and casting the treated molten mass, producing a casting;e) treating the casting further in solution by the following steps:(1) heating the casting at a temperature of 500-530 deg. C. and holding that temperature for 6-8 hours, causing dissolution of Cu,Mg,Ni and other elements in the Al matrix and obtaining a solid solution Al-Si alloy; and(2) quenching the solid solution alloy casting at high temperature into water; andf) aging the new Al-Si alloy casting by heating at a temperature of 130-230 deg. C. for 6-9 hours.