.2124 The End Of The Aluminum Alloy Quenching And Aging Process Study

The 2124 aluminium alloy was developed from traditional 2024 aluminium alloy with no remarkable strength loss. It is very suitable for the production that needs high strength and stability while working at medium temperature because of their excellent combination properties such as satisfied fracture ductility, good fatigue property, high tensile and compression yield strength and excellent stress corrosion resistance. As a result, it should have great potential at the field of aeronautics and space industry. As a precipitation strengthening aluminium alloy, the properties and applications of the 2124 aluminium alloy are obviously influenced by the ageing. Thus it is of great commercial and industry value to study its hardenability and to optimize the ageing processes.For this purpose, the Jominy end quench test and different ageing processes were carried on to thick hot-rolled plate of 2124 aluminium alloy in this paper. The evolution of the structures and properties evolution of the tested plate were investigated by optical microscopy, scanning election microscopy (SEM), transmission electron microscopy (TEM) and conductivity gauge. The obtained the results were described as follows.(1) When the diameter of the nozzle was fixed, the hardness increased with the increasing of total flow quantity of the spraying water. However, hardness decreased with the increase of the density of the flow quantity of the spraying water. The highest hardness was obtained when the nozzle diameter was 5 mm and the spraying water was 105.6 L/10 mins.(2) The mechanical properties after quenching were strongly effected by the microstructures. The distribution hardness of along Transverse direction (TD) was more symmetrical than that along Normal direction (ND).(3) The cooling rate gradually decreased with the increasing of the distance feom the quenched end. As a result, the increasing of the amount of the S'phase was induced and then lead to the descending of the machanical properties of 2124 aluminium alloy.(4) The mechanical properties of the material were remarkably effected by the morphologies, sizes and densities of the precipitates after aging. The optimum ageing schedule was 180℃/20h.(5) The tensile strength could be increased by pre-tensile deformation before aging. The strength after ageing increased steadily with the increasing of the strain of pre-deformation. The tensile strength (σb) and yield strength (σ0.2) were increased from 395.19 MPa (σb) and 346.44 MPa (σ0.2) to 496.57 MPa (σb) and 481.65 MPa (σ0.2), respectively, in the present of the 5% pre-tensile deformation, as well as decreased of elongation from 16.09% to 3.25%. Pre-rolling deformation before aging resulted in increasing of mechanical properties and decreasing the aging time to peak strength.