Effect of Retrogression and Re-Aging on Fatigue Crack Growth Behavior of Al 7075 Alloy

In this activity I used very familiarly known as two steps heat treatment called RRA is applied on AL 7075 alloy to examine the fatigue behavior. this process includes the various stages of heat treatments includes, annealing, high temperature pre-precipitation, artificial aging (T6), retrogression and re-aging. The specimens are initially heated to 473o & then quenched in water medium .the specimens are further heated to 18hr, 22hr, 26hr respectively .after this specimens are heated 230o, 250o, 270o, 290o with different time intervals 7 & 14 min respectively to enhance the strength of the material this process we call it as retrogression and re-aging .after this conducted experiment and came to know that by using RRA method we can increase the strength of the material to maximum extent.