在440℃经多向锻造加工成7075铝合金锻件.研究了锻件的显微组织和力学性能随退火温度和T73回火的变化,TEM和SEM用于分析锻件的晶粒和第二相形态.多向和大变形锻造产生平均晶粒尺寸18μm的完全再结晶组织.390℃～450℃退火使晶粒长大到3μm,但位错和第二相分布没有明显改变,这时锻件展现出较低强度和较高延性.T73回火使锻件屈服强度和拉伸强度分别提高280%和210%,而延性同退火样相比并无明显下降,断裂韧性达到51MPa,可以认为这是沉淀强化的贡献.
The forgings of 7075 Aluminum alloy were produced by a multi-directional forging process at 440℃ . The evolution of the microstructure and mechanical properties as functions of annealing temperature and aging T73 temper were studied. The grains and second phases were characterized by TEM and SEM. The multi-directional and heavy plastic deformation during forging produces fully recrystallized microstructures with average grain size of 1 8μ m. After annealing at 390℃ to 450℃ the grain sizes growth to 3μ m, but no significant change of the dislocation and second phase distributions appears, resulting in a lower strength and higher ductility. The T73 temper increases the yield strength and ultimate tensile strength by 280% and 210% respectively with no significant loss in ductility compared with the forgings annealed and produces a higher fracture toughness of 51MPa m1/2, which might be considered the result from the precipitate strengthening contribution.
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