Homogenization effect on precipitation kinetics and mechanical properties of an extruded AA7050 alloy

Abstract

Abstract In this study, effect of homogenization on precipitation kinetics and mechanical properties during aging in AA7050 alloy was investigated. The billet material produced by direct chill method was homogenized at 470 °C for 12–20 h and then extruded to form T-profile. The electrical conductivity of the alloy aged at 120 and 185 °C for 0–36 h were measured and precipitation kinetics were calculated based on the relationship between increased electrical conductivity and amount of precipitates during aging. Time dependent precipitation fraction change curves using Avrami equations revealed that precipitation accelerated as the homogenization time increased due to increased nucleation and growth rates of precipitates. Peak hardness values in aging were reached depending on the increase in homogenization time, however, lower peak hardness (∼185 HV) was determined at 185 °C aging compared to the obtained ones (195–197 HV) at 120 °C aging. Depending on the increase in homogenization time, an increase trend in strength was detected in peak aged alloys. The application of longer time homogenization and subsequent aging caused an increase in strengths. The studied homogenization and aging conditions could be a useful guide for achieving the highest strength and ideal elongation values in commercial practice for the AA7050 alloy.