Heat Treatment of Aluminum Alloy Al- 2618

Abstract

AA 2618 is age hardenable aluminum alloy which contains Cu, Mg, Fe & Ni for good strength in applications that involve exposure to high temperature i.e. aircraft engine components and automobile industries. It is typically used for rotating parts operating in service up to 200 °C and other parts operating up to 300 °C at low stresses, but usage is not limited to such applications. This alloy is different from rest of the 2xxx series alloys in that it achieves its strength from precipitation hardening as well as dispersoid hardening. The presence of these despersoids also serves to control the grain size. These dispersoids are mostly found aligned or segregated after standard heat treatment cycle. The alignment and segregation of these dispersoids is harmful to fatigue strength as it may initiate fatigue crack during cyclic loading. The current research was focused to design a heat treatment cycle to remove the segregation and alignment of these dispersoids. Heat treatment parameters (Solution treatment temperature, soaking time) are varied and their effect on the microstructure was studied. Fatigue test was also carried out after designing heat treatment cycle and data was compared for analysis, appreciable improvement in the fatigue test was observed.