论文部分内容阅读
以435℃/2 h+200℃/12 h固溶时效预处理的新型Al-Zn-Mg-Cu高强铝合金为研究对象,在温度350~400℃,应变速率0.01~1 s-1和变形量60%~80%条件下进行热压缩变形,再经350℃/0.5 h+470℃/2 h退火和固溶处理。采用光学(OM)、电子显微镜(EBSD、TEM)组织观察和测试方法,研究了时效预处理析出相粒子对热压缩变形及随后退火和固溶处理过程中晶粒组织的演变机理和规律。结果表明:(1)在400℃、0.05 s-1、60%条件下,ln Z值为24.33,发生了连续动态再结晶,获得了细小均匀的再结晶晶粒组织;经退火和固溶处理后,晶粒趋于等轴状,尺寸稍有增加,最终获得细小均匀的晶粒组织。(2)在380℃、0.1 s-1、60%条件下,ln Z值增加到25左右,晶粒沿变形方向拉长,晶界断续分布着细小的再结晶晶粒;经退火和固溶处理后,晶粒长大不明显,在变形拉长的晶粒内部均匀分布着尺寸较小的回复亚晶粒。(3)当应变速率较快或变形温度较低,ln Z值增加到约26,且变形量较大时,动态再结晶不明显,晶粒沿变形方向剧烈拉长;经退火和固溶处理处理后,晶粒长大明显,最终获得粗大的晶粒组织。
The new Al-Zn-Mg-Cu high-strength aluminum alloy pretreated by solution aging at 435 ℃ / 2 h and 200 ℃ / 12 h was used as the experimental material. Under the conditions of temperature 350 ~ 400 ℃, strain rate 0.01 ~ 1 s- 60% ~ 80% under the conditions of hot compression deformation, and then 350 ℃ / 0.5 h + 470 ℃ / 2 h annealing and solution treatment. The evolution mechanism and regularity of the grain structure of the precipitated particles by aging pretreatment during hot compression deformation and subsequent annealing and solution treatment were studied by means of OM and EBSD TEM. The results show that: (1) In the condition of 400 ℃, 0.05 s-1 and 60%, the value of ln Z is 24.33, and the continuous dynamic recrystallization takes place and fine and uniform recrystallized grain structure is obtained. After annealing and solution treatment After the grain tends to be equiaxed, the size of a slight increase in the final fine uniform grain structure. (2) Under the condition of 380 ℃, 0.1 s-1 and 60%, the value of ln Z increased to about 25, the grains elongated along the deformation direction and the grain boundaries were intermittently distributed with fine recrystallized grains; after annealing and solidification After the solution treatment, the grain growth is not obvious, and the smaller sub-grain size of the subgrains are evenly distributed in the grain with the elongated shape. (3) When the strain rate is fast or the deformation temperature is low, the value of ln Z increases to about 26, and the deformation amount is large, the dynamic recrystallization is not obvious, and the grains elongate along the deformation direction. After annealing and solution treatment After treatment, the grain grows obviously, eventually obtaining coarse grain structure.