热压缩工艺对7150铝合金显微组织的影响

Effects of Hot Compression Process on Microstructure of 7150 Al Alloy

采用Gleeble-1500热模拟机对7150铝合金在热压缩温度为300~450℃,变形量33%~87%下进行热压试验。采用光学显微镜、扫描电镜和透射电镜观察合金热压缩试验后的显微组织。结果表明,在热压缩变形过程中,7150铝合金流变应力经历了过渡变形与稳态变形两个阶段。在低于350℃下变形,变形抗力较大;400℃下变形,33%~87%变形量下,变形量越小,达到稳态变形应力越低,变形量达到60%以上时,稳态流变应力趋于稳定;变形温度达到420℃时发生动态再结晶,变形速率对组织均匀性影响巨大,变形速率越快,得到的再结晶后的组织越均匀;在400℃以下压缩变形,残留的第二相回溶速率慢,随变形温度的升高,第二相逐渐消失。

The hot compression tests of 7150 alloy were performed at 300 to 450℃ and deformation of 33%-87% by Gleeble-1500 thermal simulate machine. The microstructure of the samples after hot compression was analyzed by optical microscope, SEM and TEM. The results show that the theological stress of 7150 alloy experiences transitional and steady deformation stages during hot compression process. The deformation resistance is obviously larger when the alloy is deformed at 350℃. Under the amount of compress deformation of 33% to 87% and deformation temperature at 400 ℃, the deformation amount is smaller, the stress to reach steady state deformation is lower; then, when the deformation amout reaches above 60%, the steady state flow stress tends to be steady. The recrystallization happens when the alloy is deformed at 420 ℃. Deformation rate have huge impact on the uniformity of the microstructure. The faster the rate of deformation, the better uniformity of the microstructure after recrystaUization. The dissolved rate of the residual second-phase is slow after compression deformation at 400 ℃. With the increase of the deformation temperature, the second phase gradually disappears.