Heat treatment of natural aging aluminum casting alloys

Abstract

AbstractAbstractA number of 7xx aluminium casting alloys are based on the ternary Al–Zn–Mg system. These alloys age naturally to high strength at room temperature without a high temperature solution and aging treatment. Consequently, they have the potential to deliver properties nearly equivalent to conventional heat treated (T6) castings, with savings in energy consumption and manufacturing cost. In spite of these potential advantages, the natural aging alloys are seldom used. One important reason is that the natural aging process never stops, and design engineers are concerned about possible embrittlement or the development of stress corrosion sensitivity of castings after long service times. This paper describes a study of the aging of 705 alloy and proposes an artificial aging process that may be used to develop a structure appearing to have long term stability.Keywords: HEAT TREATMENTNATURAL AGINGAL-ZN-MG ALLOYS