EFFECT OF POST WELD AGING TREATMENT ON TENSILE PROPERTIES OF GTAW WELDED ARMOUR GRADE AA2519-T87 ALUMINIUM ALLOY JOINTS

Abstract

AA2519-T87 aluminium alloy is newly developed armour grade, age hardenable alloy with best mechanical properties, high impact toughness and ballistic resistance properties Because of this beneficial property it is preferable in replacement of steels in the light combat vehicles in order to reduce the weight and improves mobility. Formation of oxide layers, solidification cracking and porosity creates problems in the fusion welding of aluminium alloys. Gas tungsten arc welding (GTAW) is widely used fusion welding process for joining aluminium alloys which results improved arc stability, reduced thermal distortion, reduced residual stress and spatter free joints. By proper controlling of process parameters of GTAW, sound weld joint is achieved at welding current of 145 A, welding speed of 2 mm/s, and voltage of 16 V. Due to heating and rapid cooling cycles, the weld joints properties deteriorated due to loss of precipitates and uneven distribution of precipitates. In order to recover the lost properties, post weld aging treatments are carried. In this investigation the effect of post weld aging treatments like artificial aging (120oC for 12 hours) and solution heat treatment (530oC for 90 min) followed by artificial aging are evaluated. The microhardness and tensile properties are evaluated and characterized using optical microscope and scanning electron microscope for the three welding condition