6063 And 7003 Aluminum Alloy Organization Performance And Quenching Sensitivity Study

The effects of solution and aging on the microstructure and properties of6063and7003aluminum alloy were studied by hardness, tensile tests, electric conductivity measurement, X-ray diffraction (XRD) and electronic microscopy analysis. Meanwhile TTT and TTP curves of the above-mentioned alloys were obtained by solution-interrupted quench-electroconductivity measurement method and solution-interrupted quench-artificial aging-hardness test method respectively. And the effect of average cooling rate of quenching on Brinell hardness was investigated with quench factor analysis. On that base, the quench sensitivity of the experimental alloys was discussed. The results show that:1) The optimal heat-treatment regime of6063aluminum alloy is545℃/50min solution, water quenched, and then artificial aged at180℃for8h. On these condition, tensile strength, yield strength, elongation, Brinell hardness and electrical conductivity of the alloy reaches230MPa,212MPa,13.3%,64.9和56.4%IACS, respectively.2) TTT and TTP curves of6063alloy obtained by the interrupt quench method are "C" shape with a nose temperature at350℃and340℃, respectively. And quench sensitive temperature range280～380℃is determined from the TTP diagram. Cooling rate of quenching enough to suppress the precipitation of β" and β’phases has to be around7℃/s according to the quench factor analysis. Therefore, maintaining the cooling rate at7℃/s at the sensitive temperature interval and slowing down outside the range would be a effective way to obtain well matched properties.3) The favorable solution treatment of7003aluminum alloy is470℃/40min solution. After artificial aged at105℃for8h and then150℃for16h, tensile strength, yield strength, elongation and electrical conductivity of the alloy reaches352MPa,312MPa,12%and44%IACS, respectively.4) Fine dispersed GP zone precipitate from the supersaturated solid solution when7003aluminum alloy specimens are nature placed for72h after quenching. It can serves as the nuclear core of strengthening phase in the subsequent artificial aging process. In hence, the tensile strength and yield strength increased12MPa and20MPa compared with the specimens without nature placed, respectively.5) TTP curves of7003alloy obtained by interrupt quench method is "C" shape with a nose temperature at290℃. And quench sensitive temperature range250～330℃is determined from the TTP diagram. Critical Cooling rate of quenching is1℃/s according to the quench factor analysis.