Mathematical model to predict the strength in precipitation hardening

A number of alloys, notably most of the aluminium alloys can be heat treated by aging process. The precipitation of a second phase during aging increases the strength and hardness as well as modifies other mechanical properties. There is a wealth of information available in literature about the precipitation hardening response of various series of aluminium alloys in graphical form as plotted between property changes and aging time for different temperature. In designing a suitable precipitation hardening strategy, one can refer these graphs. However, for automatic control of aging furnace, as well as for decision making regarding optimal selection of aging condition (time, temperature combination). It is desirable to express these relationship in a formal mathematical structure. In this paper such a mathematical model is developed for AA6063 alloy, a widely used material in extrusion industry, which is condensed representation of all sigma = f(T,t) curves in that series. With additional data in this model can be further generalized for other series of aluminium alloys such that the parameter of generalized model characterize the various composition of the alloys in the series. (author)