Effects of deep cryogenic treatment, cryogenic and annealing temperatures on mechanical properties and corrosion resistance of AA5083 aluminium alloy

摘要

Effects of deep cryogenic treatment (DCT), cryogenic and annealing temperatures on micro-structural evolution, mechanical properties and the intergranular corrosion (IGC) resistance of AA5083 aluminium alloy are investigated. Results showed that as the temperature of the annealing increased, its strength decreased while the IGC resistance improved. At cryogenic temperature, strength and ductility increased drastically. Failure modes observed were ductile particle dimples at 295 K and 213 K, and a mixture of intergranular and transgranular fractures at 110 K. Specimens annealed at 150℃ and 200℃ exhibited a higher vulnerability to IGC due to the presence of high dislocation densities and heterogeneous precipitation of β-phase (AI_3Mg_2) at the grain boundaries as the continuous phase. In contrast, specimens annealed from 250℃ to 415℃ exhibited excellent corrosion resistance due to the minimisation of dislocation densities and noncontinuous distribution of β-phase. DCT marginally decreased the strength and hardness of the alloy, while increasing the ductility and IGC resistance.