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对3A21铝合金进行不同热暴露温度、保温时间和冷却速率的热处理来模拟火灾发生时的受火过程,并对其力学性能与微观组织进行评定。结果表明:当受火温度低于510℃时,冷却方式对冲击韧性影响较大,冲击吸收功在204℃空冷条件下升高65%,427℃水冷条件下升高57%;受火温度低于510℃时力学性能随受火温度升高略有降低,受火温度达到657℃时,力学性能降低29%~47%;冲击及拉伸断口中均出现韧窝尺寸大小差异增大,韧窝内出现颗粒相,随受火温度升高其微观组织由初始的细小均匀的带状织构组织逐渐粗化、弱化直至消失、再结晶、硬质相的析出、部分溶解与在晶界处再析出。
The heat treatment of 3A21 aluminum alloy with different heat exposure temperature, holding time and cooling rate was simulated to simulate the fire process during fire and its mechanical properties and microstructure were evaluated. The results show that when the fire temperature is lower than 510 ℃, the cooling mode has a great influence on the impact toughness. The impact absorption energy increases by 65% under air cooling at 204 ℃ and 57% under water cooling at 427 ℃. At 510 ℃, the mechanical properties decreased slightly with the increase of fire temperature. When the fire temperature reached 657 ℃, the mechanical properties decreased by 29% ~ 47%. The dimple sizes in impact and tensile fracture increased, With the increase of the temperature of the fire, the microstructure gradually roughened and weakened until disappeared, recrystallized and the hard phase precipitated, and the part of the microstructure was dissolved at the grain boundary Re-precipitation.