摘要
The effect of peak temperature （Tp） at 200, 300, 400, 500 and 550 ℃ on the microstructural evolution and softening behavior of the simulated heat-affected zone （HAZ） was studied in the 2219-T87 alloy by electron-backscatter diffraction, transmission electron microscopy, X-ray diffraction, micro-hardness and micro-tensile tests. The results showed that the grain size in the HAZs at 200-500 ℃ was comparable, but the number density of the strengthening precipitates （GP zones/θ′） decreased with increasing Tp. At a Tp of 550 ℃, the grain size significantly decreased and the distribution of the misorientation angles corresponded to the MacKenzie distribution. The GP zones/θ′ phase coarsened and translated into θ phases at Tp values in the range of 200-400 ℃. Increasing the Tp to 500 ℃ and above, some θ′ phases translated into θ phases and others dissolved into the α-Al matrix which led to an increase in the solid solution strengthening. The reduction of the number density of the GP zones/θ′ was responsible for the softening behavior.
The effect of peak temperature （Tp） at 200, 300, 400, 500 and 550 ℃ on the microstructural evolution and softening behavior of the simulated heat-affected zone （HAZ） was studied in the 2219-T87 alloy by electron-backscatter diffraction, transmission electron microscopy, X-ray diffraction, micro-hardness and micro-tensile tests. The results showed that the grain size in the HAZs at 200-500 ℃ was comparable, but the number density of the strengthening precipitates （GP zones/θ′） decreased with increasing Tp. At a Tp of 550 ℃, the grain size significantly decreased and the distribution of the misorientation angles corresponded to the MacKenzie distribution. The GP zones/θ′ phase coarsened and translated into θ phases at Tp values in the range of 200-400 ℃. Increasing the Tp to 500 ℃ and above, some θ′ phases translated into θ phases and others dissolved into the α-Al matrix which led to an increase in the solid solution strengthening. The reduction of the number density of the GP zones/θ′ was responsible for the softening behavior.
