Experimental investigation on hot forming–quenching integrated process of 6A02 aluminum alloy sheet

As important light-weight structure material, aluminum alloy has been widely used in automotive and aerospace industries, in which the manufacturing of parts with high strength and good dimensional accuracy has been the main task. In this paper, special device was developed to investigate the hot forming–quenching integrated process of cold-rolled 6A02 aluminum alloy sheet. Strengthening effect was reflected by Vickers hardness measuring and uniaxial tensile test. Microstructure examination was conducted to clarify the strengthening mechanism by scanning electron microscope (SEM), transmission electron microscopy(TEM) and electron backscattering diffraction (EBSD). Results show that Vickers hardness increases with solution time (<50 min) increase, and improves significantly after artificial aging. The faster the cooling rate, the greater the strengthening effect. The Vickers hardness of formed part can increase to 106.5 HV from 73 HV in cold-rolled condition or 40 HV in heated condition in hot forming–quenching integrated process (solution treatment at 520 °C/50 min, cooling by 50 °C/s, being aged at 160 °C/10 h). The corresponding tensile strength and yield strength are 315.6 MPa and 253.6 MPa, respectively. The strengthening phase is underaged dispersal GP zone with about 5 nm in size. The heat-treatable aluminum alloy sheet in rolled condition can be used directly in hot forming–quenching integrated process without any prophase heat treatment.