Experimental Study and Optimization on Solution and Artificial Aging of Cold-Rolled 2024 Al Alloy Sheet

The solution and aging experiments on cold-rolled 2024 Al alloy sheet were carried out. The parameters of solution temperature, solution time, aging temperature, and aging time were combined by orthogonal design, and their effects on the microstructure and overall performances of the 2024 Al sheet were studied. The results showed that aging temperature exhibited the most significant effect, followed by solution time and solution temperature, while the effect of aging time was slight. An integrated balance method was employed to optimize the solution and aging parameters, and the optimum heat treatment condition was determined as solution at 500 degrees Cx70 min followed by artificial aging at 180 degrees C x16 h. Compared with the orthogonal experimental results, it was found that the optimized solution parameters could lead to a higher dissolution degree of S (Al2CuMg) and theta (Al2Cu) phases on the premise of preventing excessive grain growth and over-burning. The optimized aging parameters could not only promote the precipitation of fine GPB zone and S phase, but also avoid the coarsening of S phase and narrow the precipitation free zone (PFZ) at grain boundary. By optimization, the ultimate tensile strength (UTS), yield strength (YS), elongation, hardness, and conductivity of 2024 Al sheet reached the excellent values of 527 MPa, 411 MPa, 12.5%, 148.9 HV, and 37.4% IACS, respectively.