Research of Heat Treatment Process of AA6022 Aluminum Alloy Sheet Prepared by Electromagnetic Oscillation Twin Roll casting

Abstract:

Based on the principle of sub-rapid solidification, AA6022 aluminum alloy sheets for automotive were successfully prepared by electromagnetic oscillation twin roll casting technology. In order to improve the comprehensive mechanical properties of the end products, the heat treatment process of the sheet was studied. Combined with OM, SEM, EBSD, macro hardness and tensile test, the effects of different heat treatment parameters on the microstructure and mechanical properties of sub-rapid solidification sheet were studied. The results show that the composite application of Al-Ti-B grain refiner and electromagnetic field can significantly improve the proportion of fine equiaxed grains. Solution + pre-aging treatment can significantly inhibit the natural aging hardening effect, enhance the natural aging stability of alloy sheet, and improve the stamping formability and paint hardening increment of alloy sheet. Under the optimized conditions (560 ℃ × 5 min + 150 ℃ × 5 min + 30 d at room temperature + 175 ℃ × 30 min), the yield strength, tensile strength, elongation, macro hardness and r value of the alloy sheet increased from 258.98 MPa, 295.7 MPa, 10.65%, 47.6 HV and 0.663 of 1# sample to 295.71 MPa, 322.01 MPa, 16.09%, 61.2 HV and 0.753 of 4# sample, respectively.

Key words:AA6022 aluminum alloy; Electromagnetic twin roll casting; Heat treatment process; Microstructure; Mechanical properties