Analysis of AA2XXX/AA7XXX friction stir welds

Abstract

Abstract Comparable microstructures and mechanical properties are obtained for the different AA2139-T8/AA7020-T651 joints welded in the range 600–1000 rev.\u2009min−1 / 250–550\u2009mm.min−1 as rotation and advance speeds. Joints exhibit tensile properties as good as 77%–79% of the yield strength and 88%–96% of the ultimate tensile strength of the AA7020 base material. Except for the high speed conditions that failed in the nugget, all joint variants failed in the heat affected zone (HAZ), which is also consistent with lower hardness properties. This drop in hardness in the HAZ is produced by reaching and keeping for a short time a critical temperature during welding between 225 and 260\u2009°C. Such a combination of dissimilar alloys offers conservative mechanical properties for a large range of welding parameters suitable for the assembly purpose of high-performance structural components.