Effect of artificial ageing temperature in T6-heat treatment on the mechanical properties of dissimilar metals weld between AA5083 and AA6063

Abstract

Aluminium AA5083 is commonly utilised in constructing ship hull shells, which are welded with aluminium AA6063 to act as stiffeners. However, the joints often suffer structural damage, such as longitudinal and transverse cracks in the dissimilar weld area, particularly in the Heat-Affected Zone (HAZ) of AA6063, which includes frames, brackets, and collars. To enhance the mechanical properties of AA6063, T6 heat treatment is commonly employed. The given study investigates the impact of temperature in artificial ageing during the T6 heat treatment on the microstructure and mechanical properties of the dissimilar materials welding between AA5083 and AA6063.The T6 heat treatment variations involve a solution treatment at 540C for 6 hours, followed by quenching and artificial ageing at temperatures of 158C, 200C, and 230C for 6 hours, followed by air cooling. The T6 heat treatment variations involve a solution treatment at 540C for 6 hours, followed by quenching and artificial ageing at temperatures of 158C, 200C, and 230C for 6 hours, followed by air. The weld joints were visually inspected and examined using radiography, then characterised by microstructure investigation and tensile and impact tests.The study's findings reveal that the T6 heat treatment significantly improves the mechanical properties of AA6063. However, the T6 heat treatment does not notably affect the mechanical properties of AA5083, the fusion line and the weld metal area. Among the artificial ageing temperature variations, the highest mechanical properties are achieved at 200C, while the lowest mechanical properties are observed at 230C.Aluminium AA5083 is commonly utilised in constructing ship hull shells, which are welded with aluminium AA6063 to act as stiffeners. However, the joints often suffer structural damage, such as longitudinal and transverse cracks in the dissimilar weld area, particularly in the Heat-Affected Zone (HAZ) of AA6063, which includes frames, brackets, and collars. The paper focused on the influence of artificial ageing temperature in T6 heat treatment on the microstructure and mechanical properties of the dissimilar metals welding between AA5083 and AA6063.The optimum artificial ageing temperature in T6 heat treatment for the dissimilar metals welding between AA5083 and AA6063 was 200C. The method can be applied in ship structures where AA5083 is typically utilised for constructing the hull shells, while AA6063 is employed as stiffeners.