Effect of electromagnetic forming–heat treatment process on mechanical and corrosion properties of 2024 aluminum alloy

Abstract

The 2024 aluminum alloys are used in a wide range of industrial applications, and improvement in their formability and serviceability is key in the manufacturing process. Electromagnetic forming (EMF) has proven to be an effective means of improving the formability of aluminum alloys. By combining EMF and heat treatment process, three samples of 2024 aluminum alloy were designed: Sample A (annealing + EMF + solid-solution + aging), Sample B (solid solution + EMF + aging), and Sample C (solid solution + pre-aging + EMF + aging). The effects of three heat treatment regimens on the properties and microstructure of 2024 aluminum alloy were studied by hardness test, intercrystalline corrosion, and exfoliation corrosion, as well as by microscopic characterization techniques including scanning electron microscopy and transmission electron microscopy. The results show that the dislocations-induced deformation could shorten the time to peak aging and led to the increase in peak strength. Sample C exhibited the highest strength and sample A exhibited the highest elongation and corrosion resistance. The microscopic results show that the differences in properties were mainly influenced by the distribution of precipitated phases and the width of the precipitation-free zone. The discrete and coarse grain boundary precipitations make sample A have excellent corrosion resistance. The fine and dense precipitated phases provide good strength for samples B and C, but also reduces the elongation. This research has important implications for rational formulation based on the combination of EMF and heat treatment processes for the fabrication of Al–Cu–Mg alloys. Conclusionsmay be made more concise. They should focus on the mechanisms responsible for high strength or corrosion resistance rather than the values obtained that are shown in results.